Vietnam-U.S. Defence Cooperation: A Three-Decade Pivot in the South China Sea

Vietnam-U.S. Defence cooperation represents a remarkable transformation in modern foreign relations, evolving from post-war engagement to a comprehensive partnership driven by shared strategic interests. This evolution, spanning three decades, has been deliberate, shaped by strategic calculations, and a patient navigation of historical legacies. The relationship has progressed from diplomatic normalization in 1995 to the establishment of a Comprehensive Strategic Partnership (CSP) in 2023, reflecting mutual efforts to address regional security challenges and converging geopolitical interests.

The Three-Decade Pivot

To understand the development of Vietnam-U.S. Maritime security cooperation in the South China Sea, it’s crucial to examine the three phases of their defence relations. Each phase has been shaped by distinct challenges and opportunities within the regional security environment.

1995-2009: Symbolic Engagement

The initial phase, from 1995 to 2009, occurred in the post-Cold War context, requiring both countries to overcome historical legacies and establish basic trust. High-level visits were infrequent, focusing primarily on humanitarian issues, such as accounting for missing in action (MIA). During this period, the South China Sea was not a strategic priority for the U.S., and naval displacement from the Philippines and Russia from Vietnam left China as the predominant naval power in Southeast Asia. Early U.S. Naval visits, like the USS Vandegrift in 2003 and the USNS Mercy in 2008, were diplomatic gestures rather than operational partnerships. Vietnam restricted port calls to single, non-strategic harbours, maintaining tight control over cooperation.

2010-2020: Institutionalizing Cooperation

The period from 2010 to 2020 marked a fundamental shift, driven by China’s increasing assertiveness in the South China Sea. Secretary of State Hillary Clinton’s 2010 statement at the ASEAN Regional Forum (ARF), affirming U.S. National interests in the South China Sea, provided political cover for deeper engagement [1]. The U.S. And Vietnam established the Political, Security, and Defence Dialogue (PSDD) in 2008 and the Defence Policy Dialogue in 2010, providing structured platforms for discussion. The lifting of the U.S. Lethal arms embargo on Vietnam in 2016 symbolized this transformation, though Vietnam initially refrained from major weapons purchases.

2021-Present: Comprehensive in Rhetoric, Restrained in Practice

Since 2021, despite rhetoric about growing strategic alignment, Vietnam-U.S. Military ties remain relatively modest and non-combat in nature. Cooperation has focused on multilateral exercises like Southeast Asia Cooperation and Training (SEACAT) and humanitarian assistance/disaster relief initiatives like Pacific Partnership. Vietnam has not participated in the Rim of the Pacific (RIMPAC) exercise since its debut in 2018. While the CSP was elevated in 2023, actual defence cooperation remains limited. Vietnam’s recent joint army exercise with China, alongside declining participation in SEACAT and RIMPAC, demonstrates a prioritization of regime security cooperation with Beijing.

The South China Sea in Vietnam-U.S. Defence Cooperation

The trajectory of Vietnam-U.S. Relations from 1998 to 2025 is marked by increasing complexity, including high-level meetings and naval port calls. The relationship has evolved through three phases, driven by building trust and South China Sea security dynamics.

Vietnam views the U.S. As a “necessary partner” in sustaining the regional balance of power and maritime stability, given its frontline role in the South China Sea disputes and its interest in preventing dominance by a single power [1]. Cooperation enables the U.S. To strengthen regional deterrence and access, while providing Vietnam with resources to address security challenges. The USS Ronald Reagan Carrier Strike Group’s visit to Da Nang in June 2023, the third U.S. Aircraft carrier visit since 2018, exemplifies this ongoing engagement [1] and [4].

Key Takeaways

• Vietnam-U.S. Defence cooperation has evolved significantly over three decades, driven by shared interests in regional security.
• The South China Sea has been a primary catalyst for increased cooperation, but Vietnam maintains a cautious approach to avoid antagonizing China.
• Cooperation remains focused on non-lethal capacity-building and multilateral activities.
• Vietnam prioritizes strategic autonomy and balances its relationships with both the U.S. And China.