Thailand is one of only two treaty allies of the United States, yet in contrast to the US–Philippines Alliance, the US–Thai Alliance is often overlooked in public discourse. Ever since the end of the Cold War, the US–Thai Alliance has struggled to maintain relevancy among policymakers, as the geopolitics of the world today finds little common security concern between the two nations that previously built the base of their alliance. With America’s values-based diplomacy often clashing with Thailand’s undemocratic tendencies, there has been a move by the Thais towards the Chinese in security relations. While there remain some areas of common interest between Thailand and the US, both parties have only marginally maintained the alliance, and without any action by both parties, it seems that the alliance is doomed to become nothing more than words on paper.

Introduction

Thailand is one of only two US-treaty allies in Southeast Asia and, historically, played a significant role in US foreign policy during the Cold War. Thailand and its monarchy served as a bulwark against Communism in the region (Handley, 2017). As with many Cold War alliances, the collapse of the USSR and America’s “unipolar moment” created questions on the necessity of such partnerships. While alliances with NATO members, Japan, and the Republic of Korea have persevered, the US–Thai Alliance has floundered in recent decades. Thailand is rarely mentioned by US policymakers in a region already widely neglected by US foreign policy. With both nations lacking major strategic interests, the alliance lacks coherence and has left it on a continual decline, even as the US commits greater attention and resources to the Indo-Pacific. This divergence has left both sides to put only the minimum amount of effort into maintaining the alliance.

Foundations of the Alliance

The 1954 Manila Pact founded the Southeast Asia Treaty Organization (SEATO) between the US, France, Britain, Thailand, the Philippines, Pakistan, Australia, and New Zealand. SEATO was meant to act as an “Asian NATO” style defense agreement that further provided defense for South Vietnam, as well as pre-Communist Cambodia and Laos. The end of the Vietnam War and the refusal of other Southeast Asian nations to join led to its dissolution in 1977; however, US alliances with Thailand and the Philippines would be preserved (Chai & Guan, 2024). The earlier 1962 Thanat-Rusk Communique reinforced US commitments to Thailand's defense and led to US support in the development of the Thai military (Bureau of Far Eastern Affairs, 1962). 

During the Cold War, Thailand acted as a bulwark against communist threats in Indochina and China, and acted as a crucial US partner in the region in that regard. The Buddhist monarchy and influential military in Thailand were seen by US policymakers to be a reliable deterrence against communism in the region (Handley, 2017). During the Vietnam War, the Thai government allowed the US Air Force to use several air bases in Thailand, facilitating sorties into Vietnam as well as covert sorties in Laos. At its peak, the US military presence in Thailand reached a height of 50,000 personnel (Ruth, 2017). Furthermore, Thailand sent 40,000 troops to support South Vietnam in the conflict, while engaging in its conflict against the Communist Party of Thailand, which received support from Vietnam and China and targeted US bases (Ruth, 2011). The Vietnam War was the peak of the US–Thai Alliance, with high levels of military-to-military cooperation and close diplomatic ties. These ties built the modern foundations of contemporary military cooperation and the role the US plays as a major military equipment supplier to the nation (Fulco & Chuanren, 2023). 

US–Thai Defense Relations Post-Vietnam

The US withdrawal from Vietnam and the following fall of South Vietnam and Cambodia to communist forces hampered relations between the nations. The Mayugez Incident in 1975 saw the US conduct a rescue operation from Thailand’s U-Tapao airbase without the permission of the Thai government. The situation was further exacerbated by the US gaining permission from the Thai military to bypass the civilian government. When planning the operation, US Secretary of State Henry Kissinger stated that the action would upset the Thai government but “the Thai military will love it” (Lamb, 2018). The incident caused a diplomatic incident with protests erupting outside the US Embassy in Bangkok, and the Thai government claimed the action was a violation of their sovereignty and demanded the removal of US troops. By 1976, American troops had left Thailand. With the end of US involvement in Southeast Asia and US rapprochement with China, Thailand’s role in American foreign policy diminished as interests diverged. 

The end of the Cold War removed the ideological threat both nations shared, leaving the alliance without a common threat. The 1997 Asian Financial Crisis further hampered relations between the two, with the US providing no direct aid to Thailand and a minimal contribution to the International Monetary Fund’s aid package (Moss, 2018). The US pushed to keep Thailand under the IMF’s stringent regulations for aid, while at the same time, the comparatively untouched China provided more appealing and substantial aid to the nation (Marciel, 2023). This episode fueled resentment among many Thais against their ally and built the groundwork for greater economic cooperation between Thailand and China. The September 11th attacks and subsequent Global War on Terror focused US attention on the Middle East, with Asia of secondary importance to policymakers. While President Bush designated Thailand as a major non-NATO ally, and anti-terrorism military cooperation was expanded between both nations, the relationship remained limited. The alliance lacked significant shared goals or threats, and non-military engagement with Thailand was limited as Washington’s attention lay in the Middle East. 

Relations deteriorated in 2006 following the military coup against Prime Minister Thaksin Shinawatra, with the US denouncing the coup and suspending military assistance to the nation. It nosedived following another military coup in 2014, with Washington actively distancing itself from the government and the Thai government openly criticizing the US. The open breakup between the two saw Thailand approach China for greater economic and defense ties. While relations improved steadily afterward, the alliance today remains distant at best, with minimal commitments made by both sides in facilitating the alliance as dynamics shift in the region.

Thailand, China, and Great Power Competition

While an ally of the US, Thailand remains ambivalent about the US–China competition that has emerged in recent years. The post-Cold War US–Thai relationship has long had to cope with Thailand’s tendency for military coups and undemocratic practices to the chagrin of Washington. As was seen in the 2006 and 2014 coups, Washington is willing to cut military aid and confront the Thai government on matters of democracy and human rights, leading to mistrust in the US by Thai leaders in the reliability of the US as a supportive ally. Furthermore, Thai officials are continually frustrated by the restrictions of the IMF and US economic development aid, creating further strains on the alliance (AFP, 2014). 

By contrast, China provides an alternative for partnerships in the region for the Thais. Contrasting the US priority on shared values, China’s authoritarian government holds no reservations about the anti-democratic tendencies of Thai politics. Traditionally, the US is Thailand’s primary arms supplier, but with the heavy restrictions placed on US equipment alongside the high cost, Thailand has pursued Chinese equipment. Since 2016, Chinese equipment sales to Thailand have surpassed those of the US (Yaacob, 2025). With joint military exercises (JMEs) between the US and Thailand cut post-coup, Thai–Chinese JMEs have grown in size and scope with increasing cooperation in air, sea, and land exercises. While these exercises are less sophisticated than those in the US, Thai–Chinese military ties continue to grow and pose the possibility of surpassing the US as the primary defense partner for Thailand (Sato & Yaacob, 2023). On the economic front, Thailand has pursued greater Chinese investment, especially through the Belt and Road Initiative (BRI). The post-2014 coup saw a major push for closer Chinese economic ties as the government saw China as an investor that would ignore Thailand’s internal politics and withhold the stringent restrictions of IMF aid and Western investment. With BRI projects such as the Sino-Thai high-speed railway project providing great economic benefits to the nation and buttressing the political elite’s popularity, China’s economic presence in Thailand is largely welcomed by the government (Busbarat et al, 2023).

Reviving the US–Thai Alliance?

Despite the stagnation of the alliance, there remain areas of cooperation for both nations. The US and Thailand cooperate in the oldest international JME in the Cobra Gold Exercise alongside other US partners and allies in Asia (Vincent & 122nd Theater Public Affairs Support Element, 2024). Furthermore, the two cooperate heavily through the International Law Enforcement Academy in Bangkok to provide law enforcement training in Southeast Asia. Both nations further cooperate in combating human and drug trafficking. Myanmar’s Civil War provides a shared interest for the alliance, with the US wary of a failed state in Myanmar and Thailand eager to end the conflict bordering it. Yet, there has yet to be an agreement between the two on how to effectively address the conflict (Goyer, 2024).

Despite these developments, the US–Thai alliance will still struggle to grow and will likely continue to stagnate as disagreements between Washington and Bangkok on strategic priorities and political values hamper the growth of ties. Washington firmly sees China as a strategic rival and regional threat and will continue to engage in competition with China. By contrast, China presents Thailand with a more dependable partner to develop its economy and tackle security threats in the region, and Thailand largely does not see China as a major security threat like its neighbors, Vietnam and the Philippines. Unlike America’s favored Southeast Asian ally in the Philippines, Thailand has no immediate catalyst for disputes like the South China Sea; thus, China is not perceived as a threat. Furthermore, while strides have been made in Thailand’s democracy, it remains imperfect by the standards of Washington. The controversial blockage of the popular Pita Limjaroenrat’s Future Forward Party by the government, alongside the dissatisfactory liberalization of Thai political and legal systems, has clashed with Biden’s values-based foreign policy. President Trump’s Second term has strained relations with America’s closest allies, and it is unlikely that he will facilitate the strengthening of the alliance with Thailand in the future. 

Conclusion

The US–Thai alliance was always perceived by US policymakers as a secondary partnership to those in Europe and East Asia since the Cold War. While military-economic relations between both nations were strong in the Cold War and reached their peak during the Vietnam War, the alliance has failed to find a place for itself in the post-Cold War world. America’s values-based foreign policy has alienated much of the Thai political elite, placing China as a preferred partner in economic and military cooperation. With both nations lacking any major shared strategic interests, the alliance will continue to stagnate and struggle to maintain its relevance in the coming years. However, both are eager to avoid a complete public breakup and will continue to contribute the minimum to maintain the alliance. With Washington and Bangkok lacking a cohesive objective, the alliance will continue to stagnate and flounder, only maintained by the desire to avoid poor publicity for both governments, an alliance likely doomed to fail.