Defense diplomacy redefines Korea’s role in Indo-Pacific region

Moon Keun-sik

The Indo-Pacific has become the most dynamic — and at the same time, the most unstable — strategic space in the world today. More than 60 percent of global trade passes through the sea lines of communication in this region. At the same time, U.S.-China strategic competition, North Korea’s nuclear and missile threats, disputes in the South China Sea and rising military tensions in the Taiwan Strait overlap and reinforce one another, making the region more critical to global security than ever before.

As reflected in last year’s meeting between the defense ministers of the United States, Australia, the United Kingdom and Japan, instability in the Indo-Pacific now directly translates into risks for global supply chains. What happens in this region no longer remains a regional problem. It affects energy markets, raw materials, financial flows and the stability of the global economy. It is not an exaggeration to say that Indo-Pacific security has become a global priority.

In this environment, a crucial change is underway in how security cooperation is built. Declaratory statements and occasional joint exercises are no longer sufficient to generate real deterrence and trust. What matters now is not what is written on paper, but what works as a system. As a result, the center of gravity in security cooperation is shifting toward defense diplomacy — long-term partnerships built around weapons systems, industrial cooperation and joint operations.

Japan offers an instructive example. In its 2023 Free and Open Indo-Pacific strategy, Tokyo placed maritime security at the core of its regional policy, strengthening integration with the U.S. alliance, enhancing cooperation between its Maritime Self-Defense Force and Coast Guard, and developing joint operational planning. This approach demonstrates how defense cooperation can be turned into an enduring strategic framework.

The essence of defense diplomacy is not arms sales. Defense cooperation must expand to cover joint training, maintenance, repair and overhaul (MRO), technology transfer, personnel exchanges and doctrinal integration. Over time, this builds both military interoperability and political trust. Once a weapons system is adopted, it shapes a country’s operational concepts and force structure for decades. For that reason, defense cooperation creates relationships that are effectively irreversible. This is what distinguishes defense diplomacy from other diplomacy.

In an era of open-source intelligence and constant monitoring of China’s gray zone activities in the South China Sea, defense networks also become platforms for real-time information sharing. Nowhere is this more important than in the maritime domain. Ships, submarines, maritime patrol aircraft and command and control systems do more than add firepower; they establish common standards for managing sea lanes and responding to crises.

The sea lanes that connect the South China Sea with the Indian Ocean are not the battlefield of any single state. They are the shared lifelines of many. Their stability cannot be guaranteed by one navy alone, but only through a network of interconnected defense partnerships.

In this context, Korea occupies a uniquely advantageous position. It maintains a firm alliance with the United States, while at the same time being viewed by many Indo-Pacific countries as a pragmatic and politically nonburdensome partner. Korean defense systems — from K2 tanks and K9 self-propelled artillery to FA-50 fighters, submarines and frigates — have already proven their value through a combination of high performance, reasonable cost and reliable supply chains. This is not merely reflected in export success; it signals Korea’s structural integration into the Indo-Pacific security architecture.

Korea’s defense diplomacy also has the potential to link major strategic frameworks. In discussions about Australia-U.K.-U.S. expansion, trilateral Korea-U.S.-Japan exercises and regional capacity-building efforts, Korean defense industry and naval expertise can serve as connective tissue between allies and partners.

Moreover, defense diplomacy does not remain confined to the military sphere. It extends into energy, shipbuilding, offshore engineering, cyber and space, creating a platform for comprehensive economic security cooperation. Defense is the most practical and actionable language through which security, industry and diplomacy can be integrated in the Indo-Pacific.

Korea’s arms exports to Indo-Pacific countries have expanded significantly since 2025, reinforced by credibility gained in markets such as Poland and Peru. Yet challenges remain. Beyond trilateral Korea-U.S.-Japan exercises, Korea should promote a multilateral MRO hub for the region. Technology transfer must be accompanied by robust security controls and localization support. For Association of Southeast Asian Nations states that seek strategic autonomy, Korea’s role as a “non-China option” is a major strategic asset.

For Korea, defense must be understood not as a sales business but as a diplomatic instrument to shape the Indo-Pacific order. The goal is not simply to sell equipment, but to build relationships in which countries operate together and share responsibility. Deterrence is not created by rhetoric; it emerges from repeated cooperation and accumulated trust.

The answer to Indo-Pacific security will not be found in grand declarations, but in steady, disciplined defense diplomacy. The power that prevents war is built not after the first shot is fired, but through preparation in peacetime. What Korea must construct today is not just a larger arsenal, but a durable architecture of trust. That is the foundation of its role as a true global pivotal state.

Ret. Navy Capt. Moon Keun-sik is visiting professor of Hanyang University Graduate School of Public Policy.