The South Seas and Islands in Vietnam’s Maritime Strategy: Position and Development Potential

Over 1,000 kilometers of islands and archipelagos make up Vietnam’s southern coastline. The following points are emphasized in the article based on surveys and secondary sources: (1) the benefits of the Southern Sea and Islands’ geographic location, environmental conditions, and natural resources; (2) the Southern Sea and Islands’ role in Vietnam’s marine economic development strategy; and (3) approaches to the sustainable development of the Southern Sea and Islands in Vietnam’s overall marine and island development strategy. The findings of the study indicate that the Southern Sea and Islands have abundant and diverse potential in terms of energy, maritime transport, ecosystems, and tourism, serving as a critical location for national security and defense for the region and the whole country. The development of marine and island values in the southern region of the country is a key component of Vietnam’s marine economic development strategy, which also emphasizes harmonious growth. Focusing on synchronized and harmonious actions is essential in the process of taking advantage of the Southern Sea and Islands’ benefits for the process of global economic integration. It is also important to promote the involvement of numerous economic sectors in the process of utilizing and sustainably growing the marine economy.


Introduction
The 21st century is considered as the "Century of the Ocean" by strategists, each maritime country is required to satisfy 3 strengths: marine economics, marine science and integrated marine management [1].Today, most of maritime countries pay great attention to the maritime strategy and consider it an organic part of the two strategic tasks of national construction and defense.Vietnam is located on the west coast of the East Sea, a large and important sea of the world.According to the provisions of the United Nations Convention on the Law of the Sea in 1982, Vietnam's sea area is over 1 million square kilometers, with a coastline of more than 3,260 kilometers (ranked 27th out of 156 countries with sea in the world), including 28 provinces and coastal cities, and a population of about 27 million people.Furthermore, Vietnam also has thousands of islands near the coast and offshore, with 66 inhabited islands [2].
The South has 19 provinces and cities divided into 2 sub-regions: the Southeast (also known as the East) which includes 5 provinces and 1 city, and the Mekong River Delta (also known as the Southwest or the West) with 12 provinces and 1 city in the south of Vietnam.With an area of about 64,400km 2 , the South accounts for about 19.4% of the country's total area.The North is adjacent to the Central The South seas and islands connect with the mainland and the Southeast sea of the East Sea with a length of nearly 1,000 km; moreover, there are about 195 large and small coastal islands and archipelagos with rich and diverse development potential [3].The South sea stretches through 9 provinces and cities from Ba Ria -Vung Tau to Kien Giang (Ba Ria -Vung Tau, Ho Chi Minh City, Tien Giang, Ben Tre, Tra Vinh, Soc Trang, Kien Giang, Bac Lieu, Ca Mau), with 2 cities (province), 2 towns, 28 coastal districts and 3 island districts [4].The South Sea is adjacent to the Gulf of Thailand, the Malay Peninsula, through the Basi Strait, the Sulu Sea and the Malacca Strait connecting to the Pacific Ocean and the Indian Ocean, which shows that this is a potential area for marine economics development as well as national defense and security.
Figure 2. Study area in southern Vietnam showing the nine coastal provinces [5] IOP Publishing doi:10.1088/1755-1315/1247/1/0120083 For a long time, the South Seas and islands have played an important role in the National Maritime Strategy, which allows comprehensive development of marine economic sectors such as: maritime economy, marine products, marine tourism, marine mineral exploitation, island economy, coastal urban development, renewable energy development, with significant contribution to the economic growth of the country.At the same time the region maintains its role as a front line protecting the southern border of Vietnam, and a gateway to international integration.Over the years, Vietnam's focus on investment in promoting the potential of the South Seas and islands for economic development and ensuring national security has brought about important results.However, the promotion of the potential of the South Seas and islands still has many limitations and is not equivalent to their existing potential, especially because of the lack of sustainability.

Materials
Materials analysed for the purposes of this research include: (1) resolutions of the Communist Party of Vietnam on seas and islands; strategies, decisions, documents, directives, guidelines, statistical yearbooks, final reports... by the Vietnamese government as well as by central agencies, departments, branches, provinces and cities in the South Ministries related to seas and islands; (2) research works (books, journals, theses, dissertations...) of Vietnamese and international scholars related to the published research issue; (3) data, field survey materials collected by the authors.

Research methodology
This research is based on the methodological basis of dialectical materialism and historical materialism of Marxism -Leninism, combined with Ho Chi Minh's thought and the views lines of the Communist Party of Vietnam, and selectively acquired knowledge of historical science related to the topic.
For this research, we use the following main research methods: (1) Secondary data collection method: We collect secondary information from domestic and foreign works, resolutions of the Party, policies and laws of the State, reports of agencies and departments from central to local levels, data from the General Statistics Office and data sources collected on articles, journals, websites and some information from related books; (2) Field investigation method: We collect primary information through field surveys.This is a particularly important method in this study to assess the potential of the South seas and islands, thereby proposing reasonable and feasible solutions; (3) Synthetic analysis method for data simulation: The article uses simulation methods to process research data, applies data analysis software, and functions in Microsoft Excel 2010 for calculation and forecasting.The results of the analysis of these secondary data are evidence for the general assessment bout the potential of the seas and islands of the South.This is also the basis for us to calculate and provide solutions; (4) Statistics and comparison methods: presenting research results in the form of tables, charts, graphs, functions, etc. to assess the current situation of the sea and southern islands in Vietnam's marine development strategy, combined with comparative methods to assess the potential capacity of the South seas and islands compared to other regions in the country; ( 5) SWOT analysis and consultation methods: using the method of consulting relevant agencies and experts to support the research.Furthermore, using the SWOT analysis method to analyse and evaluate the strengths, weaknesses, opportunities and challenges in promoting the potential of the south seas and islands, thereby proposing solutions to promote sustainably their strategic values of the in the future.

Strategic values of the South Seas and islands
The South Seas and islands not only have a unique natural geographical position, an important geostrategic position, but also possess diverse and rich resources.In this section, we focus on presenting

Strategic values on defense and security
As a part of the East Sea, the South Seas and islands have extremely important geopolitical significance.During the development process of the southern region, the seas and islands are the living and development space.Generations of Vietnamese people over the centuries have made many efforts to reach out to the sea, with the purpose of mastering the seas and islands for economic and security purposes.In the depth of historical perception and reality, the South Seas and islands have an important position and role in ensuring economic development, asserting sovereignty and promoting international economic integration.Since the first centuries AD, Phu Nam was an ancient kingdom that existed and prospered thanks to sea trade with a wide network of exchange with the countries, connecting with maritime routes passing through the South Sea at that time [6].In addition, the rich skills of Phu Nam inhabitants in "building a boat with eighty nine feet long, sixty seven meters wide, head and tail like a fish" [7], is also an important feature and helps Phu Nam to move towards the sea.Thanks to strong fleets of ships, Phu Nam people were able to organize oceanic voyages and trade with the economic centers of the ancient world.
However, the decline of Phu Nam in the 6th century and the collapse in the 7th century led to the decline of the Southern region for ten centuries.It was not until the 16th and 17th centuries, when the Vietnamese and Chinese immigrants came to explore, that the southern region had seen positive changes it quickly became a new economic force in the region with the interlacing of waterway system created by the Mekong, the Dong Nai and the Vam Co rivers, convenient for sampans and large boats to take advantage of water flows across the crowded commercial centers at that time [8].The recent studies also show that, in the 18th century, a system of international trading points in the Southern Delta was formed such as: Cu Lao Pho (Dong Nai), My Tho (Tien Giang), Ha Tien (Kien Giang) [9], Bai Xau (Soc Trang), Long Ho (Vinh Long), Saigon -Ben Nghe,... apart from other centers of the Southeast Asia such as Champon, Chaiya, Ligor, Singora (Thailand) and Bang Plasoi, Rayong, Chanthaburi, Kampot... (Cambodia), Batatvia, Palembang (Indonesia).An open "water frontier" has been formed, helping to connect the Southern Delta with other regions in the vast Southeast Asia [10].
In addition to expanding management rights on the mainland, Lord Nguyen also established a mechanism to manage the South Seas and islands.In addition to the Hoang Sa team patrolling and managing the Hoang Sa archipelago, Lord Nguyen also developed the Bac Hai team, managed by the Hoang Sa team [11].The task of the Bac Hai team is to "take small fishing boats to Bac Hai regions, Con Lon isle and Ha Tien islands, then find the things from ships and tortoise shells, sea turtles, abalone, sea cucumbers" [12].It can be seen that, although it has only stopped in the paramilitary form (a combination of military and civilian), we can clearly recognize the sea-oriented thinking of Lord Nguyen through the Hoang Sa and Bac Hai teams.The fierceness of the Cochinchina government is also reflected in the struggle to protect the sovereignty of the seas and islands.In particular, a remarkable event in the southern waters and islands during this period was that, the Cochinchina government drove the forces of Company rule in India out of Con Dao in 1703 [13].Meanwhile, in the waters of the Gulf of Thailand, since the Mac dynasty surrendered to Lord Nguyen (1708), the territory under the control of the Lord Nguyen was extended to the Gulf of Thailand.Accordingly, the relationship of the Cochinchina government with the other countries in the region such as Chenla and Siam was no longer limited to the mainland but extended to the sea and island space [14].
The importance of the South Seas and islands are continuously inherited and enforced by the Nguyen dynasty in a systematic and continuous manner.As a dynasty governing a large territory stretching from Nam Quan Pass to Ca Mau Cape, the Nguyen Dynasty had strong activities in the enforcement and protection of sovereignty over the seas and islands.The event in 1816 when King Gia Long claimed sovereignty over the Hoang Sa archipelago on the basis of planting a flag and sending marines stationed to collect taxes and patronize fishermen in the area, [13] as well as the organization, measurement and mapping of the country; including the system of islands and archipelagos of King Minh Mang [15].In the future, these document become solid evidence for affirming Vietnam's sovereignty over seas and islands.
The construction of defense bases in the seas and islands is always highly appreciated, for example, Minh Mang, in 1835, gave Decree: "In the south of our country, it has a lot of sea, therefore, the navy is very important.It is advisable to train people so that they master sea routes, then it will be useful for our country.At present, the navy has been supplemented in Kinh, and the coastal localities also have marines.Therefore, the generals, leaders, rulers and administrators in Kinh, the Wards, Communes, Districts, and Warlords in the provinces, depending on your own sailors, such as boats, sails, crosses, masts, mooring lines, boatman, sailors, are required to practice thoroughly and masterly, and then must practice to clearly know the routes of river, sea, deep and shallow, the difficult, the easy, and isles, islands, reefs, rapids, must abstain...If you do not try to make your best efforts that the marines are not trained ready, the technique is not sophisticated, the guard has loopholes, then you will be punished even more severely" [16].Besides training the navy, the court also paid attention to the construction of a coastal defense system.In the 12th year of Minh Mang era (1831), the court ordered the Governor of Gia Dinh citadel to review the places in Ha Tien with key terrain where the fortress could be located.On that occasion, Kim Du fortress was built with 160 soldiers and 3 Ole boats, becoming an important pole of Ha Tien [17].In 1832, Minh Mang commanded to build fortresses, equipped them with guns, weapons, ships and send defenders in Con Dao and Phu Quoc, and provided weapons for the people to defend themselves [17].The coastal defense system of the Nguyen Dynasty in the south is recorded by "Khâm định Đại Nam hội điển sự lệ" (Administrative Records of Dai Nam) as following (see table 1) [18].During its rule, the Nguyen Dynasty repeatedly organized campaigns to measure and map sea areas throughout the country, particularly in the South Sea "Xiêm La quốc lộ trình tập lục" (Collected Routes to the Country of Siam) is a document of the routes (water, land) from the outh to Siam and some other countries in Southeast Asia as well as some islands in the Gulf of Thailand.This rather special document was used to illustrate the map of Siam presented by the envoys Tong Phuoc Ngoan and Duong Van Chau after the mission trip to Siam (1809) [19].It can be said that the southern coastal waterway was described quite fully, reflecting the royal court's interest in this sea.
Thus, the Nguyen court, especially during the reigns of Gia Long and Minh Mang, had specific strategies and actions to strengthen the fortification system, build a fairly complete coastal defense force, created conditions for the boats and people to be armed and for defense against pirates, in order to protect and exercise sovereignty over seas and islands in the South.In order to strictly manage the activities of the ships, the Nguyen Dynasty also issued many edicts with diverse contents such as those on patrolling to inspect ships through the seaports and setting sails in groups; to closely manage the situation of ships entering and exiting the creek and estuary in the form of "Work Diary", organize search for boats in distress or seal the boats when necessary [20].However, due to many factors, this defensive power became weaker in later dynasties.
During the French colonial period, the system of seas and islands in the South was of interest to the French authorities.One of the important issues of the South Seas and islands during this period was the establishment of a maritime management and exploitation area in the Gulf of Thailand between Vietnam and Cambodia.According to the conception of previous feudal governments, the border between countries was not clearly defined according to the current system of geographic coordinates.The invasion of Western colonialism into Southeast Asia was also accompanied by the introduction of Western topographic and geographic techniques.Before the controversy of Ha Tien and Kampot provinces about the surrounding islands and waters, on January 31, 1939, Governor-General of Indochina Jules Brevié wrote a letter to the Governor of Cochinchina and the France Ambassador in Cambodia expressing his views on the dividing line to patrol and control disputed islands between Vietnam and Cambodia [21].Since then, a dividing line between Vietnam and Cambodia is commonly known as the Brevié line [22].The ambiguity and informality of the Brevié line has led to controversy in the process of establishing the maritime border of the two countries until today.
Currently, in the context of increasing exchanges and contact between countries, the seas and islands of Vietnam in general and the South in particular are becoming increasingly busy; furthermore, the future prospects of maritime trade and shipping are continuously promising, the South sea issues related to disputes and conflicts over the past three decades have become complex and unpredictable.With the rugged terrain of the territory, there are wind-tight bays, interspersed with flat coasts, favorable for the shelter of ships and troop movements by sea; and possessing abundant natural resources.Simultaneously, due to central position in Southeast Asia and location near important maritime routes in the Gulf of Thailand and in the East Sea; the South, especially the southwest region, has a full range of favorable conditions for the development of international relations with countries in ASEAN, Cambodia and Thailand at first, by both land and waterway.In particular, it is possible to establish a coastal economic belt around the Gulf of Thailand, by Vietnam, Cambodia, Thailand and Malaysia; therefore, the South Sea always affects geopolitics during early modern period to the modern era.
Moreover, the South Sea has two outpost island systems, Phu Quoc and Con Dao, which have extremely important geopolitical significance.As the largest island district in the country, located in the waters of the Gulf of Thailand, with a special outpost-border position, Phu Quoc becomes an outpost in the Gulf of Thailand, protecting the southwest region and the common territorial integrity of the whole of Vietnam [23].With its position near the shore and forming a "historic water area" between Vietnam and Cambodia, Phu Quoc has helped the territory of Vietnam expand thousands of square kilometres out to sea.Meanwhile, Con Dao with 3 islands (Tai Lon, Bong Lang, Bay Canh) is selected as a benchmark to establish a baseline to calculate the breadth of the territorial sea in the East Sea, creating a large internal water area, including the entire Cuu Long oil and gas tank [4].The location of Con Dao, which is near the maritime route connecting the two major economic centers of the world, Singapore and Japan, only 60km from the maritime route through the Kra canal project, has important geopolitical significance [24].In the past, due to its important strategic position in terms of military and politics, in the 16th-17th centuries, Con Dao was watched by Western colonial groups, considered as "the entrance to Malacca Strait, a shelter for European ships on their way to China"; the British took the island in 1702 [25].Here, it is possible to monitor and control the activities of ships on a large scale, and Con Dao can be developed to become a large and strong military base in the southeast sea of Vietnam.Besides the two outpost islands (Phu Quoc and Con Dao) in the South Sea, there are many other coastal islands with important geo-economic and geopolitical values (see table 2) [3].As a result; the sea, especially the present system of islands and island districts of the South Sea has an important strategic position in the cause of national construction and defense.On the islands, it is possible to establish the bases to control the sea and airspace; control the activities of ships and boats to ensure national security and defense, to build the economy, protect Vietnam's sovereignty and entire territory; furthermore, it is the basis for Vietnam to reach out the sea and ocean.

Strategic values on economics
Besides the political strategy position, the South sea and island area also has the greatest economic value, which is reflected in the mineral and energy resources, marine biological resources, tourism resources and transport.
Mineral and energy resources: Vietnam has a large continental shelf area, which has long been assessed as having great oil and gas potential, with estimated reserves of about 4-8 billion of m 3 converted oil.Oil and gas in Vietnam is divided into 17 lots with many different oil and gas reservoirs.Thus, the mineral and energy resources in the South Seas and islands are very rich, both in the block of water, on the bottom and within the seabed.In the South Sea, many prospective oil-and-gas sedimentary basins have been identified, in which Cuu Long and Nam Con Son basins are assessed as having the most favorable petroleum prospects and exploitation conditions, with total estimated reserve of about 10 billion tons of converted oil [26].According to statistics, the oil reserves here are about 400 million m 3 of oil, accounting for about 93.3% of the reserves of Vietnam, and about over 100 billion m 3 of gas, accounting for 16.2% of the national reserves, which is mainly concentrated in Ba Ria -Vung Tau province (in the Southeast region) [27].In the Southwest region, the mine reserves are forecasted to fluctuate in the range of 200-500 million tons of converted oil and gas reserves of about 138.2 billion m 3 , accounting for 35% of the country's reserves.Currently, 2 billion m 3 gas are being exploited and taken to the land each year [28].Oil and gas are considered as a premise and an important source of raw materials for the development of the southern region in particular and the whole country in general.This is an important source of raw materials and fuel for the petrochemical industry and electricity industry, as well as an important export items nowadays.In addition to oil and gas, the South Sea also has other minerals such as: peat, limestone, building stone, clay, iron, and semi-precious stone.Of these limestone for cement production has reserves of more than 440 million tons, while peat reserves are estimated at 13.1 million m 3 [30].

Marine biological resources:
The South has a large sea area with a high degree of biodiversity, characterized by a large ecosystem of tens of thousands of hectares of lagoons and enclosed bays, hundreds of hectares of tidal flats and mangroves, a sea grass ecosystem, a coral reef ecosystem and island ecosystem; therefore, it is rich in flora and fauna resources.These ecosystems bring direct economic benefits, support agro-forestry-fishery industries as well as indirect services.According to statistics of Vietnam Fisheries Magazine, seafood reserves in the Gulf of Tonkin are about 750,000 tons, 712,000 tons in the Central Coast, 1,141,000 tons in the Southeast Sea, and about 1,141,000 tons, 610,000 tons in the Southwest Sea and 1,036,000 tons in the middle of the East Sea [31].Therefore, excluding the area in the middle of the East Sea, the South Sea has 1,751,000 tons of aquatic products, 2.4 times more than the Gulf of Tonkin and 2.5 times more than the central region [32].According to other statistic data, the aquatic resources of the South Sea are diverse in species and rich in reserves.The southwest region has more than 80 species of high economic value and demersal fish account for 70% of the species, with fish and shrimp reserves of about 610,000 tons, the allowable exploitation capacity is equal to 44% of the reserve (i.e., it can reach over 268,000 tons each year) [33].According to the General Statistics Office, the total fishing production of the whole country in 2020 is 3,896,533 tons, of which the Southern region is 1,890,080 tons (see table 3) [34].Among the seafood of the South Sea, pelagic fish play a major role.The recent assessments show that the average pelagic fish reserves in Vietnam's waters are about 2,744,900 tons and the exploitation capacity is 1,372,400 tons.In the Gulf of Tonkin reserves are 390,000 tons and exploitation capacity is 156,000 tons; Central reserves are 500,000 tons and exploitation capacity is 200,000 tons; Southern reserves are 840,000 tons and exploitation capacity is 335,600 ton (in which the South East: reserves are 524,000 tons and exploitation capacity is 209,600 ton; Southwest: reserves are 316,000 tons and exploitation capacity is 126,000 ton) (see table 4) [35].In particular, the southeast region has a key fishing ground of national significance (Ba Ria -Vung Tau) with high seafood reserves that allow exploitation and cultivation of precious aquatic species such as shrimp, tortoise, and squid, pelagic fish, demersal fish, snails or scallops Particularly, the southwestern sea area is considered to be the region with the most developed marine fisheries in the country, because this area has many large shrimp and fish fields, and marine fish reserves accounting for ½ of the country's reserves [36].As for marine plants, there are 15 species of seagrasses in Vietnam, distributed from the North to the South and along the islands.Statistics show that seagrasses of the South Sea are very diverse, mainly concentrated in the Southwest with 10 species, with an area of 11,750 ha, (seagrass beds in Phu Quoc, Kien Giang are the most diverse with 9 species, total distribution area is more than 10,000 ha).According to statistics in the whole sea of Vietnam, 374 species and 80 varieties of coral have been discovered; of which, 195 species and 55 varieties in the West Gulf of Tonkin, 320 species and 73 varieties in the Central and Southeast regions; the Southwest has 264 species and 64 varieties, mainly growing in the coastal areas of offshore islands such as Nam Du archipelago, Tho Chu archipelago, and Phu Quoc island [37].Sea grass beds and coral reefs are the habitat, feeding, breeding and nursery areas of many valuable marine species [33].Besides, the South Seas and islands also have many rare marine species such as tortoises, sea snakes, birds and marine mammals, etc.In particular, 3 species of mammals are common in Con Dao waters: Long-snouted Dolphin (Stenella longirostris), Blue Whale (Balaenoptera musculus) and Dugong (sea cow).These are 3 marine mammals that need to be protected, especially the Dugong, which has only been discovered in Con Dao in 1995.Currently, Dugong is the object of protection on a global scale [38].
Mangrove forests in the South are also very rich and diverse: they cover tropical tidal coastal estuaries with an area of about 250,000 hectares; of which, Ca Mau province has the highest biological level in the country (32 main mangrove species and 32 other species of the same family) [39] and over 500 species of seaweeds.The southern coastal region has the Mekong River system that carries millions of tons of alluvium into the sea every year, with a tidal height of 2.5 -3.5 m.The area is warm and sunny all year round, with average temperature of 26°C and no winter season, facilitating the growth of mangroves [40].Mangroves are a source of nutrients for many food chains, a place to breed, nourish and spread biological genetic resources for the sea and surrounding areas.The mangrove ecosystem is also considered as a buffer zone between the sea and the mainland, erosion control and alluvial coastal development.In the area near the sea, black mangroves often develop, followed by the mangrove and apple mangrove in the mainland.Mangroves regulate the air in the region, making the climate cooler, reducing maximum temperatures and ranges of temperature.Can Gio mangrove ecosystem is likened to a "lung" regulating Can Gio climate, giving Ho Chi Minh City a new biosphere.Mangroves are important in conserving biodiversity for coastal zones and maintaining potential biological resources such as mangrove forests in Ca Mau and Lam Vien in Can Gio.

Marine tourism resources:
The natural tourism resources of the South Seas and islands are very rich and diverse.The south seas and islands have many beautiful natural sand beaches, beaches, and caves, such as: front beach, back beach, Dau beach, Ho Coc beach, Ho Tram beach, Long Hai beach, Thuy Duong beach (Ba Ria -Vung Tau); Khai Long beach (Ca Mau); Mui Nai beach, Dai beach, Sao beach, Truong beach… (Kien Giang).Furthermore, the South Sea also has small unspoiled beaches in Ba Ria -Vung Tau and Kien Giang, which have not been named yet or sandy and muddy beaches from Can Gio (Ho Chi Minh City) to Ca Mau which have not yet been invested and exploited.The South Sea possesses many islands and archipelagos of scenic value, with great potential for tourism development.
Although the South has 9 provinces bordering the sea, most of the islands here are concentrated in two provinces of Kinh Giang (Southwest) such as: Phu Quoc, Tho Chu, Nam Du archipelago, Hai Tac, Ba Lua; and Ba Ria -Vung Tau province (southeast region) such as: Con Dao.In which, Con Dao consists of 16 large and small islands, with a total area of 76.71 km 2 .The ideal natural conditions of Con Dao are not only reflected in the geographical location but also in the oceanic climate with cool sea breeze blowing throughout theyear.The harmonious interweaving between the mountains and the sea has created a green ecosystem and provides fresh air to the island in all seasons [25] which allows the development of many types of marine tourism such as: ecotourism, resort, sightseeing, swimming, sports, recreational fishing and scuba diving; Phu Quoc is the largest archipelago in Vietnam (with 22 large and small islands), located in the Gulf of Thailand, identified as an eco-tourism center with many beautiful landscapes.In 2019, Phu Quoc was voted as one of the best tourist destinations in Asia by CNN (US media) and in the top 5 top autumn destinations in Asia -Pacific (2019) [25].Therefore, the South Sea fully converges conditions for the development of modern types of tourism such as: resort, swimming, eco-tourism, marine scientific research and sport tourism (see table 5).Not only that, the South also has many UNESCO-recognized coastal and island Biosphere Reserves such as: Can Gio Mangrove Biosphere Reserve (recognized by UNESCO in 2000) with diverse communities of terrestrial and aquatic fauna and flora in the large delta of the estuaries of the rivers of Dong Nai, Saigon and Vam Co. Can Gio Biosphere Reserve is not only the ideal place for scientific research and eco-tourism, but it also has great significance for environmental protection [41]; similarly to Kien Giang Coastal and Marine Biosphere Reserve (recognized by UNESCO in 2016).The area has three core zones belonging to U Minh Thuong National Park, Phu Quoc National Park and Kien Luong -Kien Hai Coastal Protection Forest.Kien Giang Biosphere Reserve contains a rich, diverse and unique landscape and ecosystem.Here, there are Melaleuca forests on wetlands, forests on rocky limestone mountains, marine ecosystems; in which typical seagrass beds are associated with rare animals, like sea cows [42].Ca Mau Cape Biosphere Reserve (recognized by UNESCO in 2009) has many typical ecosystems such as: mangrove forest ecosystem, Melaleuca forest ecosystem on peat land wetland and marine ecosystem.Each ecosystem preserves its rich biological and geological resources with high conservation value [43].Furthermore, the South is also an area with many national parks, including 3 coastal national parks such as: Ca Mau Cape National Park, U Minh Thuong National Park, U Minh Ha National Park, and two national parks on islands such as: Phu Quoc National Park, Con Dao National Park.These national parks support habitats of a variety of animals, plants, coral reefs, seagrass beds, precious aquatic species [44].These values can be incorporated into thematic tourism programs to attract tourists to visit, learn and research.In addition, the South Seas and islands also have other natural tourism resources such as: the system of caves, lagoons, lakes, rivers and streams, creating many favorable conditions for the development of various types of tourism.

Transportation development potential:
The southern region, with three sides facing the sea, is very convenient for exchange with the countries in the region and the world.One of the important features of the South Sea is the interlaced river system of the tributaries of the Mekong, the Dong Nai, and the Vam Co rivers downstream, forming large estuaries such as Can Gio, Xoai Rap, Tieu, Dai, Ba Lai, Ham Luong, Co Chien, Cung Hau, Dinh An, and Tran De.It is the complex between the estuary system and the maritime route passing through the South that has formed a convenient waterway transportation system for the trading and transportation of goods in the historical process, contributing to the very early development of the commodity economy in the South.In terms of the efficiency of marine economy, transportation potential in the South Sea is signifcant.Along the southern coast, there are many seaports such as: port groups in the Southeast (Saigon port, Vung Tai -Thi Vai port, Cai Mep port) [45]; port groups in the southwest region (Hon Chong, Binh Tri, Ha Tien, Hon Khoai, Nam Can, Phu Quoc...), and the fishing port system, typically: Tac Cau, Nam Du, An Thoi (Kien Giang); Rach Goc, Song Doc (Ca Mau); Binh Dai, Thanh Phu (Ben Tre); Ganh Hoa (Bac Lieu); Loc An, Cat Lo, Phuoc Hiep; Tan Phuoc, Ben Da (Ba Ria -Vung Tau) [46].Along with the system of ports; warehouses, coastal road transport systems in the south and island routes including trans-island roads, roads around the island and the airport system of Rach Gia, Phu Quoc, Con Dao and others allcontribute to facilitate the use of marine economic potential associated with national security and defense.

The Southern seas and islands in Vietnam's maritime strategy
As a country with a long coastline, a system of islands and archipelagos stretching from North to South at important geopolitical positions of the international maritime route, the Party and the State of Vietnam have set out important strategies for the development of marine and island economies since Renovation (1986).On May 6, 1993, the Politburo issued Resolution No. 03-NQ/TW on a number of tasks to develop marine economy in the coming years, this is considered the first thematic resolution of the Vietnam Communist Party on marine economic development strategy.The Resolution recognized certain limitations of the pre-renovation period in developing the marine economy: "In general, our country's marine resources have been exploited at a low level so far.The understanding of our country's marine potential is still rudimentary and one-sided.The basic investigation and scientific research on the sea, even for some of our country's advantages on sea, have not yet created the necessary scientific and technological basis for the development of industries and marine economic regions as well as the planning and policies on the sea.Socio-economic infrastructure in coastal areas and islands is still lacking and outdated, especially communication and transportation" [47].The strategy is to set up the goal of turning Vietnam into a strong country on the sea: "Developing the marine economics is both exploiting marine resources, affirming sovereignty and enhancing the ability to protect territorial integrity and territorial sea; building seas and islands, especially some key areas, into "a level" and "a leader" to promote the whole country's development; exploitation associated with ecological environmental protection [47].
Then, Resolution No. 09-NQ/TW dated January 9, 2007 on Vietnam's marine strategy to 2020 was passed with the focus on "developing all potentials of the sea" [48].The resolution determines that by 2020, strive to turn Vietnam into a strong country in the sea, enriching from the sea, firmly ensuring national sovereignty in the seas and islands, making an important contribution to industrialization, modernization, making the country rich and strong... Striving to 2020, the marine and coastal economy will contribute about 53-55% of the country's total GDP [49].
Continuing to realize the goal of turning Vietnam into a maritime power in the changing domestic and global situation, on October 22, 2018, the Central Committee of the Communist Party of Vietnam issued a Strategy for sustainable development of Vietnam's marine economy to 2030, vision to 2045.The strategy affirmed the view that the sea is a constituent part of the sacred sovereignty of the Fatherland, a living space, a gateway to international exchanges, closely associated with the cause of national construction and defense.Vietnam must become a country strong in the sea, rich from the sea, with sustainable development, prosperity, security and safety.Sustainable economic development is associated with ensuring national defense and security, maintaining independence, sovereignty and territorial integrity, strengthening foreign relations and international cooperation on the sea [50].The indicators on sea and ocean governance, coastal zone management are required according to international standards, reaching the level of the above -average countries in the world.The economy of 28 coastal provinces and cities is estimated at 65-70% of the national GDP, the per capita income of coastal provinces and cities is 1.2 times or more higher than the average income of the whole country.The strategy for sustainable development of the marine economy to 2030, with a vision to 2045, shifts the priority focus to sea tourism, with more emphasis on environmental protection and marine economics development.Vietnam has also fully joined international treaties on the environment and the sea and actively builds a legal system for marine management; actively promoted negotiations to settle maritime disputes and signed three delimitation agreements and two joint exploitation agreements, creating conditions for clearly defining sea areas under UNCLOS to implement maritime strategies [49].
Southern seas and islands have many strategic values both in terms of economy, security -defense and cultural system; therefore, in Vietnam's maritime strategies, the South Seas and islands are always identified as having an important strategic position.Resolution No. 03-NQ/TW dated May 6, 1993, identified the key point in the strategy of developing the South seas and islands economics being Ho Chi Minh City -Bien Hoa -Vung Tau, with the central port cluster being Vung Tau, Thi Vai, Saigon and may review to develop Can Tho and Hon Chong ports in the Southwest region.The migration and building of a rich economy in key islands and archipelagos such as Phu Quoc and Con Dao are also specified.Marine economics sectors such as oil and gas, fishing, tourism, etc. are considered as priorities for economic development in the region.In the sustainable development strategy of the marine economics to 2030, with a vision to 2045 (October 22, 2028), with the goal of turning Vietnam into a strong and rich country from the sea, the South seas and islands' development strengths are identified as follows [50]: Southeastern sea and coastal areas (Ba Ria -Vung Tau, Ho Chi Minh City): developing international container seaports, seaport logistics services, maritime safety assurance services, oil and gas extraction and processing industries, supporting industries and petroleum services; southwestern sea and coastal areas (Tien Giang -Ca Mau -Kien Giang): focusing on building and developing Phu Quoc into a strong international marine eco -tourism and service center; developing gas industry, gas processing, gas power, renewable energy, aquaculture, seafood exploitation, logistics services, fishery infrastructure and connecting with major economic centers in the region and the world.Furthermore, the construction of Ca Mau and Rach Gia cities is envisioned so that they become strong marine economic centers of the country, comparable to urban areas in the southwest key economic region and providing a solid base to promote the comprehensive exploitation of the southwest sea resources.Investing in the construction of transportation routes, connecting seaports with domestic and international regions, areas and localities, serving the development of marine economic zones [51].The strategy has identified key and breakthrough marine economic sectors by 2030 such as: tourism and marine services; maritime economy; exploiting oil and gas and marine mineral resources; aquaculture and fishing; coastal industry, renewable energy and new marine economics sectors [50].With the advantages of natural resources and geomorphology, the South Seas and islands have great potential and strengths in developing key economic sectors identified in the marine economy development strategy by the end of 2045.
It can be said that the potential and prospects for the development of South Seas and islands in the present and in the future are substantial.In reality, the South Seas and islands are receiving great attention from ministries and sectors in the construction and planning of marine space with the goal that by 2030, a vision to 2045, and the area will become an economic zone the key to developing tourismmarine economy of the country.The infrastructure system in the coastal areas and on the islands has been focused on investment, creating a fundamental change in economic development, serving as a solid basis for reaching out the sea; at the same time, it will become a solid defense line protecting sovereignty, sovereign rights and national jurisdiction over Vietnam's seas and islands [52].Thanks to the implementation of the Marine Strategy, coastal and island economic zones in the South have been established, attracting a lot of investment capital, making important contributions to economic growth, exports, and increasing budget revenue for the region and whole country as well as creating jobs.In addition, the marine economics sectors in the South are focused on developing synchronously, focusing on exploiting regional strengths such as: oil and gas exploitation and processing; maritime economy (including fleet building, seaport system development and repair industry, logistics services); seafood economy and aquaculture; sea and island tourism and coastal resorts; development of industrial parks and coastal urban areas.
However, in reality, the economic scale of the South Sea is still modest, development is not commensurate with its potential and the industry structure is not reasonable.The system of marine science and technology research facilities, human resource training for marine economy; the facilities for monitoring, forecasting and warning of sea and natural disasters, search and rescue centers, etc. in coastal areas are still small with rudimentary equipment and weak capacity.Adverse changes in the marine environment are recorded; environmental pollution has occurred in seafood processing establishments, tourism areas, and residential areas.Marine biodiversity and aquatic resources are seriously and unsustainably declining.Regarding tourism activities: in addition to Phu Quoc, Con Dao is being heavily invested, with many services for tourists, but other islands are being developed mostly spontaneously, without adequate attention to the environment and landscape.The cause of these IOP Publishing doi:10.1088/1755-1315/1247/1/01200814 limitations is due to extreme developments in global climate change; the organization and management apparatus for sustainable development of the marine economy is still inadequate, such as: the marine economics development strategies and planning of the sea areas and each locality have not yet created linkages and mutual support; the coordination among ministries, branches and localities in the management of marine economics development is still limited; The organizational structure in the management of seas and islands in localities has not been unified, human resources for management in the field of seas and islands are still thin without rich experience [50], [51], [52].

Some solutions for sustainable development of strategic values in the South Seas and islands
The South Seas and islands have many strategic values both in terms of economy, security -defense and in terms of cultural system.In order to promote those strategic values and develop sustainably the values of the South Seas and islands, it is necessary to have a strategic orientation and solution based on reference to past experiences.This task puts the responsibility of the government and the people (both in the coastal areas and inland residents) of the southern provinces in a position towards the values of the seas and islands.The adequate promotion of the past achievements and the development of progressive policies will contribute to creating synergy in the preservation and protection of Vietnam seas and islands.Furthermore, these contributions are also the basis to form a driving force to help Vietnam implement a strategy of sustainable development of the marine economy by "turning our country into a strong country in the sea, enriching from the sea, firmly ensuring national sovereignty over seas and islands, making an important contribution to the cause of industrialization and modernization, making the country rich and strong" [53].
In Vietnam's history, the sea and the land have had an organic relationship as the two basic components forming the material and spiritual strength of the nation.In order to affirm the country's sustainable strength, the establishment and protection of Vietnam's sovereignty always requires focusing on asserting sovereignty over seas and islands; When the sovereignty of the seas and islands is violated, its consequences are serious harm to the strategic and core interests of our country.In the context of the general perception of the connection between the mainland and the seas and islands, the land always plays a decisive role in affirming the scope, territorial sea space, maritime rights and sovereignty of our country [54].Historically, Dai Viet's government is very skillful and pays attention to consolidating and establishing international relations and implementing a flexible foreign policy to create a balanced and stable life for the exploitation of natural resources, strengthen the security of the South, and create an in-depth strategic defense, even during periods of great prosperity [55].
Since the territory of the southern region still has many differences related to historical perception, then the experience of acquiring the southern land by Lord Nguyen -mainly through the peaceful exploitation in line with diplomatic negotiation activities to affirm territorial sovereignty should be considered [56].Specifically, while still consistently asserting its legal sovereignty in the south, Vietnam needs to skillfully handle the complicated and intertwined relationships with the countries adjacent to Vietnam borders.Efforts to regulate foreign relations are a very important contribution in the process of creating a stable context in the southern part of the country, making a great contribution to the country's sustainable development.
On that basis, the consolidation of sovereignty and the development of strategic values of the marine and island resources of the South should be placed in the harmonious handling of relations between the ethnic groups living on this land.Because not only Vietnamese people but also Hoa, Cham, Khmer and other ethnic groups have participated in the process of preserving, fighting and expanding the territory of the southern region, both on land and in the seas and islands The nation's maritime orientation comes from the maritime tradition, including the cooperation of many ethnic groups to gradually master the seas and islands such as Van Don, Cu Lao Cham, Cu Lao Re, Con Dao, Phu Quoc, Tho Chu and the ocean islands of Hoang Sa and Truong Sa [57].The maritime tradition of the Vietnamese in the historical development in general and the South in particular has the strong participation of the whole nation.This process includes harmonization, tolerance of individual values, reconciliation of differences and finding a common understanding to jointly protect sovereignty and jointly exploit the seas and islands.Therefore, the mobilization of solidarity and harmonious handling of ethnic relations in the South -a land characterized by the inclusion of many ethnic groups in the development process, is very important for (1) maximizing the existing potential, understanding and spirit of mastering the south seas and islands by the ethnic groups in the southern region; (2) maintaining stability and balance in the region because these are very important factors to ensure the effectiveness of policies.Especially, the experiences and lessons from Lord Nguyen's "being close to the people" policy in Cochinchina with implementing a policy of opening up, gaining people's hearts, arousing and encouraging all new development factors, the construction of a strong military force and having a strong sea view, have created the basic foundation for Lord Nguyen to maintain and consolidate his firm position in Cochinchina [58].This is an important basis for Vietnam to develop harmonized policies and encourage the participation of ethnic communities in solidarity in exploiting the resources of the South Seas and islands.
The promotion of the strategic value of the South Seas and islands needs to be placed in the context of international economic integration, in which emphasis is placed on effectively utilizing and promoting economic factors related to the valuable resources of the South Seas and islands.Historically, the leaders of the Cochinchina government selected economic factors, in particularly, foreign trade, as the main support in the context of strong regional economic development, influencing the prosperity and decline of every country and nation.The Lord Nguyen's policy of open economics and overview created the basis of awareness to encourage foreign businessman to trade with preferential and fair policies [59].The favorable location being surrounded by the sea, can help expand domestic and international economic exchanges, creating favorable conditions for the South to soon develop an open mind towards integrated values [60].This is a favorable condition to promote the process of international economic integration on the basis of international exchange and integration through activities and festivals of the South Seas and islands.In order for the international economic integration to achieve a sustainable effect, the advantages of geographical location, natural conditions and resources of the South Seas and islands need to be further promoted.
In the process of exploiting the advantages of the south seas and islands to serve the country's international economic integration, it is necessary to pay attention to the following measures: (1) "synchronicity" among departments, between policy orientation and specific implementation with longterm orientation; (2) "sustainability" -development that involves protection of the natural resources and the environment of seas and islands, etc., in particular, attention must be paid to the conservation of resources for future generations to use; (3) considering the "human factor" -that directly creates the quality of international economic integration through training activities, improving skills and professionalism; (4) strengthening "people's support and confidence" for the Party and State's decisions, especially policies on seas and islands; (5) encouraging the participation of many economic sectors in marine economy development, especially the participation of foreign actors.All these activities are focused on the spirit of "economic development" closely linked with "ensuring security -defense" and reflected correctly and practically the Party's guidelines and policies, which the 11th Party Congress's document pointed out that it was necessary to "strongly develop the marine economy commensurate with the position and potential of our country's sea, associate the development of the sea and island economics with the guarantee of national defense and security, and the protection of sea sovereignty" [61].

Conclusion
Experiences from feudal governments in the history of Vietnam have proved that even in terms of the behavior of the feudal government under the influence of objective or subjective factors, it cannot be denied that the seaward policy of the feudal government had positive values and provides many meaningful reference lessons for the development of the South in the context of globalization and international integration.In the process of exploring the South Seas and islands of the country, generations of Vietnamese people have gradually gained deep understanding that in order to master the seas and islands, we must firstly focus on maintaining and developing Vietnam's seas and islands.In the broader term, both the mainland and the South Seas and islands are closely related to the survival and development of Vietnam.
In the 21th century, from the perspective of international economic integration, positional resources are increasingly recognized as having strategic importance, highlighting the importance of the South Seas and islands.Vietnam's maritime strategy also emphasizes the harmonious development and focuses on developing the values of the seas and islands in the South of the country.With the influence of foreign trade business, the South Seas and islands are a living space and providing many important economic resources.When Vietnam's international economic integration is increasingly interested in investment, then the development of the resources of the South Seas and islands will be considered as a strategic task.Basically, the South Seas and islands have many potentials and strengths such as (1) mineral resources, energy, (2) marine and island ecosystems, (3) tourism and marine transportation.In addition to the strategic socio-economic potentials, the South Seas and islands also play the role of a strategic space for security and defense for the region and the whole country.The South Sea is adjacent to the Gulf of Thailand, the Malay Peninsula, through the Basi Strait, the Sulu Sea and the Malacca Strait connecting to the Pacific Ocean and the Indian Ocean.In terms of historical significance, the South sea is associated with geopolitical relations during during early modern period to the modern era.Today, the increasing exchange and contact between countries has made the seas and islands of Vietnam in general and the South Seas and islands in particular become more and more bustling.The prospect of maritime trade and sea transport in the South will further hold a great promise [36].All these factors and realities make the promotion of the values of the South Seas and islands even more demanding and being an urgent task.

Figure 1 .
Figure 1.Location of the southern provinces of Vietnam

Figure 3 .
Figure 3. Vietnam's location in Southeast Asia

Figure 4 .
Figure 4. Map of oil and gas activities in the South and other areas in Vietnam[29] 12

Table 1 :
The South coastal defense system in the Nguyen Dynasty after 1832

Table 2 :
Vietnam seas and islands

Table 4 :
Reserves and fishing capacity in the sea ofVietnam [35]

Table 5 :
[32]ent status of some tourism resources in the Southwestern seas and islands[32]