ASEAN-ROK Security Cooperation in a Dual Contingency

The probability of a dual contingency — simultaneous conflicts erupting in the Taiwan Strait and on the Korean Peninsula — remains low, yet it is steadily rising. China could attempt a forcible unification with Taiwan, while North Korea could launch a military strike against South Korea. The two countries could deem that the US and allied military capacity in the region is overstretched.

Such a nightmare scenario is not hypothetical for Southeast Asia. A dual conflict would directly affect sea lines of communication (SLOC), capital flows, and regional strategic stability. South Korea’s survival under such a grave situation would partly depend on how much the ASEAN partners could absorb the shock and bolster their resilience. For ASEAN, the dual contingency would destabilise nearby waters and test its ability to maintain its centrality, protect commerce, and defend against financial and reputational fallout.

Security cooperation between ASEAN and the Republic of Korea (ROK) is undeniably one of the essential elements of regional security. Without such cooperation, regional stability would be further weakened, and both sides’ security environments would deteriorate, particularly in the face of dual contingencies. Yet, security cooperation is not fully developed. The two entities have a symbiotic relationship. South Korea’s economic lifeline runs through Southeast Asia. About 90 per cent of South Korea’s energy supplies are shipped via the Malacca Strait and adjacent sea routes. If such chokepoints are cut off due to a dual contingency, South Korea’s economy and warfighting capability would be severely damaged. Meanwhile, North Korea’s sanctions-evading networks have been exploiting the Southeast Asian environment for years; Pyongyang has moved funds as well as materials through illicit shipping, shell firms, and front companies. During a dual conflict, ASEAN states have options: they could provide humanitarian relief, an evacuation hub for operations, and diplomatic crisis mediation. Even if ASEAN does not assume a military role, its choices would substantially shape Seoul’s security environment.

In this context, the idea of reviving SEATO 2.0, or an Asian equivalent of NATO, has been floated in some circles. Yet, it is advisable for South Korea to pursue pragmatic and issue-focused cooperation, rather than attempt to construct a comprehensive security arrangement with ASEAN. The hurdles to creating a collective defence mechanism in Asia are notable. ASEAN’s preference for consensus-based decision-making, the divergent threat perceptions among the member states, and the strong preference to safeguard their own strategic autonomy render a NATO-like collective defence system a remote possibility. Some ASEAN members have close security ties with China and would likely oppose any framework that might be seen as bloc politics. The concept of collective defence would undermine cohesion, trigger a regional backlash (largely driven by China), and ultimately be largely symbolic rather than deliver practical capability enhancement.

Given the evolving security landscape in this region, the real challenge will be whether ASEAN and South Korea can reinforce maritime resilience, enforce sanctions, safeguard civilians, and stabilise supply chains through flexible cooperative frameworks.

A more feasible agenda for cooperation should be based on areas where ASEAN and South Korea share common interests.

One area for cooperation is in maritime security and sanctions enforcement. South Korea could expand its liaison presence at Singapore’s Information Fusion Centre and conduct joint simulation drills on convoy protection, maritime incident response, and crisis communications with ASEAN countries. Such actions could strengthen SLOC security even without a treaty framework. A dual contingency would intensify North Korea’s attempts to circumvent international sanctions. In response, an ASEAN-ROK task force could be set up to share watch lists, hold transhipment detection drills, and coordinate enforcement activities. Such measures would safeguard ASEAN states’ reputations and shield them from financial exposure.

A second area would be in humanitarian relief and crisis logistics. With ASEAN leadership and South Korean support, a pre-arranged accord on non-combatant evacuation, medical transfers, and safeguarding relief goods would facilitate swift civilian protection during a crisis. South Korea’s close collaboration with ASEAN’s AHA Centre would also be useful.

Finally, ASEAN and South Korea can cooperate on technological and economic resilience. From seaports to power grids, ASEAN’s major infrastructure is vulnerable to state-sponsored cyberattacks and the misuse of commercial drones. With its advanced technological base, South Korea could provide affordable counter-unmanned aircraft systems (UAS), run joint cyber incident response drills, and share expertise on critical system protection. Meanwhile, ASEAN and South Korea could streamline customs and rapidly expand production during a crisis by designating priority items such as semiconductors, batteries, and medical equipment.

ASEAN-ROK cooperation could face numerous hurdles during contingencies. Because of the varied threat perceptions regarding China and North Korea, ASEAN’s willingness for overt alignment may be weak. Legal and political sensitivities would limit base access, intelligence sharing, and joint monitoring. From South Korea’s perspective, a war on the Korean Peninsula would consume most of its capacity and naturally curtail the resources available abroad. Meanwhile, defence industrial partnerships would run into difficulties due to ASEAN’s financial limitations and fears of excessive technological reliance on South Korea. Such obstacles highlight the need for politically acceptable steps, rather than grandiose schemes for security cooperation.

Given the evolving security landscape in Southeast Asia, the real challenge will be whether ASEAN and South Korea can reinforce maritime resilience, enforce sanctions, safeguard civilians, and stabilise supply chains through flexible cooperative frameworks. In a dual contingency, ASEAN states are unlikely to join the fight on behalf of South Korea or Taiwan. Nevertheless, ASEAN can play a critical role in preserving regional openness and stability. For Seoul, investment in such network-oriented cooperation is not optional, but a strategic safeguard against the storm clouds gathering in the Taiwan Strait. For ASEAN, cooperation with South Korea is not equivalent to addressing a geographically distant crisis; that said, such cooperation would help to protect ASEAN’s sea lanes and financial systems, as well as bolster regional stability.

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