Since establishing relations in 1972, the India-Vietnam relationship has generally been seen as one of the most stable in the Asian geopolitical landscape. The two countries have maintained a foundation of traditional friendship, moderate economic cooperation, and gradually expanded defense engagements without creating significant strategic concerns for other major powers. Compared to hot topics such as the China-U.S. rivalry, the Taiwan issue, or the South China Sea dispute, the India-Vietnam relationship has rarely been the focus of attention for international policymakers.
However, that is changing rapidly.
China appears to be closely monitoring the development of India-Vietnam relations, particularly in the areas of defense, maritime affairs, and strategic technology. While China likely does not view this development as a direct threat to its national security, its real concern lies in the increasingly clear convergence of strategic interests between the two countries in areas where China holds important interests, such as the South China Sea, the Indian Ocean, and a post-U.S. security architecture in Asia.
For a long time, China was relatively comfortable with India-Vietnam relations because cooperation between the two countries was largely symbolic. In fact, since the two countries established a Comprehensive Strategic Partnership (CSP) in 2016, defense activities have mainly been limited to delegation exchanges, small-scale exercises, and political dialogue. But in recent years, China watched this relationship become more substantive at a significantly faster pace.
Currently, India-Vietnam defense relations are no longer solely centered around friendly diplomatic statements. The two sides are expanding cooperation in areas of deeper strategic significance, such as submarine training, fighter pilot training, defense industry cooperation, sharing maritime situational awareness, and defense credit support. In particular, Vietnam’s access to the BrahMos supersonic cruise missile is becoming a symbol of the increasing strategic trust between Hanoi and New Delhi.
During General Secretary To Lam’s visit to India from May 5-7, the two countries upgraded their relationship to a new level – “Enhanced Comprehensive Strategic Partnership” – and signed a joint declaration focusing on mutual assistance in defense industry development and maritime support.
From China’s perspective, these individual factors may not be enough to alter the regional military balance. But when viewed holistically, they reflect a much larger trend: India is gradually shifting from its position as a power center in South Asia to one of increasingly prominent security actors in Southeast Asia and the South China Sea.
China’s Geostrategic Concerns
From ancient times to the present day, China has viewed Southeast Asia as a space where it has exclusive influence due to its geographical location, economic scale, and the region’s trade dependence on the Chinese market. However, with the increasing presence of the United States, Japan, and Australia, and now India’s growing involvement in Southeast Asian security issues, China’s strategic environment is becoming significantly more complex.
In this context, Vietnam has emerged as India’s most important partner in mainland Southeast Asia. Vietnam possesses a strategically advantageous position on the western coast of the South China Sea, has relatively strong military capabilities within ASEAN, and pursues a foreign policy flexible enough to cooperate with multiple major powers simultaneously.
The South China Sea is at the heart of this concern. For China, the South China Sea is not just the site of overlapping territorial disputes but a space linked to its “core interests,” a matter of survival. It is a crucial strategic shipping lane for China’s trade and energy, and a key area for China’s ambition to become a global maritime power. China’s ability to project naval power into the Western Pacific and maintain its sea-based nuclear deterrence capabilities are closely tied to its control and influence in the South China Sea.
Therefore, China is particularly sensitive to the strategic presence of external powers in the region where it considers itself the center of the order. From China’s perspective, India’s increasing role in the South China Sea through cooperation with Vietnam has implications that extend beyond bilateral relations.
The oil and gas activities of ONGC Videsh in Vietnamese waters have repeatedly drawn objections from China, which argues that these projects are located in a “disputed” area. However, India has maintained its presence despite diplomatic pressure from China. This sends an important signal: India no longer sees itself merely as a South Asian or Indian Ocean power, but is viewing the South China Sea as part of its expanding strategic interests. This is increasingly concretized through India’s “Act East” strategy, which New Delhi has been focusing on strengthening since 2014. And Vietnam is the most important gateway for that expansion.
No issue better reflects the shift in India-Vietnam relations than the potential sale of BrahMos missiles. Reports of Vietnam’s interest in the BrahMos have been persistent, although the Vietnamese Ministry of Defense has never publicly confirmed it. Militarily, the BrahMos could significantly enhance Vietnam’s anti-access/area denial (A2/AD) capabilities in the South China Sea. But what worries China more is the deeper significance of this deal. If India transfers the BrahMos to Vietnam, it would reflect India’s willingness to play a more active security role in Southeast Asia, a significant increase in strategic trust between the two countries, and the gradual development of flexible defense cooperation networks outside the traditional multilateral framework by middle-sized Asian nations.
China may be accustomed to direct competition from the United States – a rival with a clear alliance structure and easily identifiable strategic logic. But “soft balancing” networks are far more difficult to counter. In this model, countries don’t openly oppose China, but instead coordinate step by step to limit Beijing’s ability to completely dominate the regional order.
The India-Vietnam relationship has most likely been perceived by China according to that model. Here, Vietnam’s policy toward China is also a key factor. Vietnam’s multilateralism and strategic autonomy make its partnerships – including with India – more unpredictable for China. In other words, China’s concern is not that Vietnam is “choosing sides,” but rather that Vietnam’s flexible foreign policy is contributing to an increasingly unfavorable strategic environment for China’s regional ambitions.
The Limits and Lingering Concerns
China also understands the limitations of India-Vietnam relations. Vietnam maintains its “four nos” policy and avoids joining military alliances against China. India itself has a strong tradition of strategic autonomy and does not want to be seen as a tool in the U.S. strategy of containing China. This makes it difficult for India-Vietnam cooperation to develop into a military alliance in Asia.
Furthermore, the relationship between the two countries still faces practical limitations regarding economic scale, technological integration, and India’s defense industry capabilities. China understands that current India-Vietnam relations are not sufficient to fundamentally alter the regional balance of power.
But what catches China’s attention is not the present but the long-term trend. The India-Vietnam relationship reflects the reality that middle powers are increasingly seeking to build, strengthen, and expand cooperative networks to protect their strategic space in the context of great power competition. And perhaps that is the deepest reason why China is monitoring the India-Vietnam relationship more closely than before. It’s not because Vietnam and India are about to form a formal military alliance, but because the two countries are gradually creating a form of strategic convergence sufficient to make the security environment in the Indo-Pacific much more complex and difficult to control than before.
