Southeast Asia’s Maritime Crossroads

By Mehmet Enes Beşer

Southeast Asia is one of the world’s most strategic sea highways where global commerce passes through, strategic rivalries, and environmental risk points meet. From Malacca Strait to South China Sea, Southeast Asian seas are as vital to global economic being as they are to Southeast Asian seas’ diversity for sovereignty and national interests. Ocean Space is no longer just free riding or naval threats anymore, though, but a realm of a broad security and expansive agenda. From gray zone coercion and submarine cable attack to piracy and climate-driven coastal erosion, Southeast Asia is confronted with mounting workload in protecting its maritime space as mounting geopolitical tension mounts.

The growth of the maritime security agenda is a consequence of a paradigm shift in threat framing. Conventional naval threats—piracy or conventional military power—are on the table, but now in addition to a list of hybrid and non-conventional threats. Grey zone activities, particularly in the South China Sea, blur the line between war and peace. Coast guard deployment, maritime militias, and offshore capability for resource development allow it to keep Southeast Asian claimants—Vietnam, the Philippines, Malaysia—on their toes short of war. It violates international law and ASEAN nations’ political will and coordinating ability to the extreme. Simultaneously, Southeast Asia becomes increasingly vulnerable to manipulation of its strategic maritime infrastructure.

Undersea cable upon which most internet and financial transactions worldwide are made traverse regional sea beds with minimal protection. The cables are in private hands, not seldom unguarded, and poorly regulated, and thus exposed targets in case of strategic sabotage or mishap. As the area becomes ever more reliant on cloud connectivity and digital economies, disruption would have implications—not just for trade, but for regional confidence and political stability. Illegal, unreported, and unregulated (IUU) fishing is only one symptom. The majority of the world’s richest marine biodiversity is found in Southeast Asia, whose fishery is severely under threat from foreign vessel intrusion, overfishing, and ineffective law enforcement. IUU fishing not only squanders valuable food commodities and liveliestones, but also amplifies trans-boundary tension and undermines sovereignty at sea. The problem is most perilous where boundary at sea is in dispute or capacity for enforcement is weakest.

Climate change further worsens the conditions. Sea level rise, ocean acidification, and intensified storms threaten coastal facilities and fisheries. Saline intrusion and coastal erosion due to sea level rise in low-lying deltaic areas such as the Mekong already resulted in displacement of people and impacts on livelihoods. Maritime security in this case cannot be divorced from climate resilience—it should have an orientation that involves a mix of defense policy, ecological management, and sustainable development.

Regional responses, however, are uneven.

ASEAN has more and more openly framed its increasing acceptance of the maritime security agenda, i.e., through forums such as the ASEAN Maritime Forum and the ASEAN Outlook on the Indo-Pacific. Operational coordination, however, is still in infancy. Different perception of threats, overlapping claims to territory, and uneven naval power deter concerted action. While Indonesia, Singapore, and Vietnam have been major spenders on maritime domain awareness, and fleet modernization, others are constrained by resources or will. Outside powers also enter the equation. United States, Japanese, Australian, and Indian Indo-Pacific policies increasingly depend on Southeast Asian maritime capacity building, under initiatives such as the Quad’s Indo-Pacific Maritime Domain Awareness program. China, too, has its own conception of the sea—seen in infrastructure, coast guard diplomacy, and naval assertiveness. These competing promises of friendship are typically followed by strategic coercion, and Southeast Asian nations must tread gingerly lest they get entrapped or beholden.

All that considered, Southeast Asia is capable of creating its own sea destiny. The regional institutions, for all the castigation they get for consensus-making, provide room for confidence-building and negotiation. Bilateral and trilateral naval patrols—i.e., the Sulu Sea ones—are evidence that focused cooperation is achievable. Greater deployment of technology—satellite monitoring, data-sharing, AI-based ocean watch—is a means to level the playing field and create openness.

But to be truly effective, maritime security efforts must go beyond periodic exercises and summit oratory. The region must be confronted in a more integrated and systematic way—one that understands the nexus between strategic deterrence, law enforcement, conservation, and cyber infrastructure. Maritime security is no longer solely the responsibility of a navy; coast guards, customs, environmental agencies, cyber regulators, and communities must be called upon as well.

Southeast Asia is not a political sea bloc, yet its maritime interdependence is stable. Its seas tie not merely cities and economies but the interests and fates of their people together. The challenge when great power rivalry is heightened and new threats emerge is not whether and if the region will react, but how, and with what coordination, transparency, and intent.

Southeast Asian maritime security will decide regional strategic stability, economic resilience, and ecological sustainability. It will not be a benign agenda to challenge, but if it is not challenged, the region will be susceptible to harm—not so much to external pressure, but to loss of sovereignty that it is intended to safeguard. The moment for maritime cooperation is now—not as a hope, but as a necessity.