Geography influences the strategic choices of all countries, but Vietnam is an interesting case of a "swing" state in comparative grand-strategy terms. The country occupies the eastern part of the Indochinese Peninsula, with an elongated coastline of 3,260 kilometres facing the South China Sea. Vietnam also sits unambiguously in continental Asia, sharing a 1,300-kilometre border with China, as well as abutting Cambodia and Laos.
This duality in Vietnam's situation, straddling Southeast Asia's geostrategic fault line, gives it unusual flexibility to develop a continental or maritime orientation. Despite a strong landwards pull in Vietnam's history, Hanoi has latterly and perhaps decisively adopted a maritime course, though the country's grand strategy remains dynamic and is actively debated among observers.
In the second half of the 20th century, Vietnam's communist leadership was absorbed by the anti-colonial struggle and national unification. The long wars against France and then the United States, when Hanoi's ideological and material allies were the Soviet Union and China (to a lesser extent), encouraged a continental disposition. Coastal supply routes were important to sustaining Hanoi's revolutionary war effort in South Vietnam, but the main axis of supply ran overland through Laos and Cambodia, along the Ho Chi Minh Trail. North Vietnam's armed forces lacked the means to contest US sea control in the South China Sea.
China forcibly expelled South Vietnamese forces from the Paracel Islands in 1974, though Hanoi maintains Saigon's claim. After reunification in 1975, Vietnam's border conflict with China in 1979 and prolonged military intervention in Cambodia throughout the 1980s ensured that Hanoi was preoccupied by land-based threats for the remainder of the Cold War, with the exception of a brief clash with China in the Spratly Islands in 1988.
In the 21st century, however, Vietnam has transformed into an export-oriented economy that depends upon freedom of navigation in the South China Sea, and beyond, to deliver its prosperity. This has influenced its threat perceptions. The majority of Vietnam's population and infrastructure is concentrated on the coast, making it vulnerable to attack from the sea. Vietnam has to defend and police the oil, gas and fish within its exclusive economic zone, as well as its territorial claims in the Spratly Islands.
If, in future, China is able to exert uncontested control within the so-called nine-dash line, and acquires access to a naval base in Cambodia, Vietnam could find itself encircled and vulnerable to blockade. Once access to seaborne trade is denied, Vietnam would suffer immediately and grievously.
The move towards a maritime strategy is evidenced by changes to Vietnam's defence capability. Despite the effects of the 2008 global financial crisis, Vietnam doubled its defence expenditure between 2006 and 2010. From 2009, it began acquiring six Russian Kilo-class submarines armed with anti-ship and land-attack Klub supersonic cruise missiles capable of hitting China.
The modernisation of the Vietnam People's Navy was officially declared a priority at the 11th National Party Congress, in 2011. The 2019 defence white paper put a seal on Vietnam's strategic reorientation by officially identifying it as a maritime nation. Vietnam is unlikely to prevail in a serious maritime conflict with China, but it has made significant investments to raise the costs of aggression.
Despite these trends, it has been argued recently that Vietnam should "look west for its survival" and refocus its strategic attention from the maritime domain to its land borders because "the balance of power on land works more in Vietnam's favour". According to this line of argument, Hanoi has little long-term hope of defending its maritime claims in the South China Sea due to the growing power disparity between China and Vietnam.
But the strategic situation on land is less severe than it may first appear. In reality, a binary continental-versus-maritime dilemma is somewhat artificial; Vietnam will continue to look landwards for its security, and to some extent for its prosperity too. Hanoi cannot overlook the possibility of invasion or incursion across its land borders. It is also the case that Vietnam's armed forces remain army dominated for historical reasons. However, China and Vietnam signed a border treaty in December 1999, which was ratified in 2000. The two sides completed border demarcation in 2009.
Although China has a dominant economic profile and significant political influence in both Cambodia and Laos, Vietnam's Southeast Asian neighbours remain sovereign states and are unlikely to allow the People's Liberation Army to launch attacks on Vietnam from their territory. Even if Phnom Penh and Vientiane agreed to host PLA ground and air forces, invading Vietnam would be prohibitively expensive, as demonstrated by Russia's war in Ukraine and, indeed, China's costly invasion of northern Vietnam 43 years ago.
By contrast, China's unilateral and expansionist actions in the South China Sea haven't faced serious consequences. Since 2009, Beijing has incrementally ramped up its claims across the South China Sea, consolidated its control in contested areas, interfered with the sovereign economic activities of other claimants within their exclusive economic zones, and militarised those features it has converted from rocks and reefs into artificial islands. China can exert pressure on Vietnam from the sea at much less risk to itself than over land, including but not limited to the use of grey-zone tactics.
If Vietnam were to vacate the features that it occupies in the Spratly Islands, China would be certain to fill the resulting vacuum, further strengthening its control. Giving up on the South China Sea would be widely unpopular with the Vietnamese public, potentially threatening the legitimacy of the Vietnamese Communist Party. Most importantly, accommodating Beijing's maritime expansionism as a fait accompli would undermine Vietnam's long-term security and that of the surrounding region. Hanoi has progressively aligned its domestic legislation with the UN Convention on the Law of the Sea and international law because its long-term interests are best served by upholding the rule of law and peaceful dispute resolution.
Vietnam's maritime strategic orientation has fostered closer economic and security partnerships with Australia, India, Japan, South Korea, the United Kingdom and the United States. As Vietnam attracts more foreign investment, including production relocated from China, it has become important to international supply chains, giving other countries an increased stake in its security. External assistance has significantly improved Vietnam's maritime law enforcement capacity, enabling it to develop its marine economy despite continuous pressure from China in the South China Sea.
Any reversal of the prevailing maritime strategy is therefore unlikely to hold water with Hanoi's key decision-makers, who have embraced a maritime orientation as essential to Vietnam's national security.
Co-written with Bich Tran, visiting fellow at the International Institute for Strategic Studies and PhD candidate at the University of Antwerp
