Amid rising tensions in the South China Sea, Indonesia, the Philippines, and Vietnam are strengthening maritime security cooperation to safeguard regional stability and uphold international law. The three Southeast Asian nations are pursuing a flexible framework that reinforces Association of Southeast Asian Nations-led regionalism while allowing each country to maintain strategic autonomy.

A growing web of bilateral arrangements has become the foundation of the emerging trilateral cooperation, particularly through operational coordination between coast guards. Analysts note that practical collaboration at sea, ranging from joint patrols to information sharing, has become the most visible aspect of the partnership.

A key development was the agreement between Indonesia and Vietnam to demarcate overlapping exclusive economic zones in the North Natuna Sea, as outlined in the United Nations Convention on the Law of the Sea. The settlement removed a long-standing maritime dispute and paved the way for expanded joint coast guard activities and deeper defense ties.

In March 2025, Jakarta and Hanoi elevated their relationship to a Comprehensive Strategic Partnership, opening new avenues for defense industry cooperation and military exchanges.

Meanwhile, the Philippines and Vietnam have intensified maritime coordination through agreements on law enforcement, search and rescue, and defense dialogue.

ASEAN forums continue supporting coordination and confidence-building among the nations.