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South Korea’s Partnership with NATO ;

From the DMZ to Brussels: South Korea's Partnership with NATO

Defence-in-Depth
Dr Bence Nemeth

Senior Lecturer in Defence Studies Education

17 April 2025

When South Korean Foreign Minister Cho Tae-yul stepped into NATO headquarters in Brussels at the beginning of April for a high-level foreign ministers’ meeting, he was not an outlier. He will be fulfilling what is now a routine role in Seoul’s increasingly strategic relationship with the transatlantic alliance. South Korea’s presence at such NATO gatherings has become commonplace, with Cho marking the fourth consecutive top diplomat from Seoul to attend. The country’s president has also attended every NATO summit since 2022, underscoring the remarkable transformation of South Korea from a distant observer to an indispensable partner.

This deepening partnership is more than symbolic. It reflects a shifting world order where deep security partnerships are no longer bound by geography but by shared values, mutual threats, and strategic necessity. From opening a diplomatic mission to NATO in Brussels, to embedding cyber experts in the alliance’s Cooperative Cyber Defence Centre of Excellence in Estonia, to hosting regular military consultations and intelligence-sharing talks, South Korea is now plugged into NATO’s operational ecosystem in ways that would have seemed improbable even a decade ago.

The Role of South Korea in Global Security

The driver behind this realignment is an increasingly volatile global security landscape and the war in Ukraine, in particular. Russia’s invasion not only awakened Europe’s defence posture but forced NATO to look eastward, toward partners in the Indo-Pacific who share its commitment to democracy, rule of law, and open societies. South Korea emerged as a natural ally, offering not only rhetorical support but real material aid: humanitarian assistance, sanctions enforcement, and, most notably, vast quantities of artillery shells sold to the United States, helping NATO arm Ukraine amid stockpile shortages.

But the collaboration runs deeper. As reports emerged that up to 10,000 North Korean troops were deployed to Russia, NATO requested an official briefing from Seoul. In response, South Korea swiftly agreed to dispatch a delegation and bolster defence coordination with NATO and Ukraine. Pyongyang’s involvement in the European theatre underscores just how global these crises have become, and why NATO’s cooperation with Seoul is more than symbolic—it is strategic. As NATO Secretary-General Mark Rutte warned, North Korean troops fighting alongside Russian forces represent a dangerous escalation.

Political Shifts and Future Prospects

This is the world that President Yoon Suk Yeol embraced during his now-ended presidency. Elected in 2022 with a vision to transform South Korea into a “global pivotal state,” Yoon made closer ties with NATO a foreign policy cornerstone. He shifted South Korea’s global orientation from a South Korean peninsula-focused security actor to a proactive democratic power, investing in multilateralism, defence exports, and values-based diplomacy. His efforts helped South Korea’s integration into NATO’s broader strategic vision, particularly through trilateral engagement with the U.S. and Japan on NATO summits, NATO-aligned arms sales to NATO members like Poland and Romania, and participation in cyber defence networks.

Yet the story of South Korea’s evolving role cannot ignore recent political upheaval. At the beginning of April 2025, the Constitutional Court removed Yoon from office after unanimously ruling that his declaration of martial law violated the constitution. The stunning impeachment of a sitting president has sent shockwaves through South Korean politics and raised questions about what direction the country’s foreign policy will take next. But even amid this turbulence, the structures of cooperation that Yoon helped build appear likely to endure.

A Strong Partnership Built on Shared Interests

Why? Because this partnership no longer relies on any one leader. As our research shows, South Korea and NATO have become enmeshed through multiple institutional and political channels, and this process started much earlier than Yoon’s presidency. The relationship is underpinned by what we describe as a "loosely-coupled security community," which is not a formal alliance, but a network of shared values, interoperability, and mutual trust, developed over nearly two decades. Whether through joint participation in NATO missions in Afghanistan or arms cooperation with European partners, Seoul has methodically built its credibility as a reliable contributor to global security.

Moreover, both NATO and South Korea perceive themselves as lacking certain strategic resources they can only secure through collaboration. NATO gains global legitimacy and operational support from a technologically advanced, democracy-anchored Asian partner. Meanwhile, South Korea, historically diplomatically constrained by its North Korea-centric posture and the static dynamics of the Demilitarised Zone (DMZ) on the Korean peninsula, increasingly leverages its ties with NATO to elevate its global profile, shape international norms, and influence multilateral dialogues.

A Partnership for the Future

This convergence is not accidental—it reflects a growing recognition on both sides of shared strategic interests. For NATO, the Indo-Pacific is no longer peripheral but increasingly viewed as connected to European security. Likewise, for South Korea, developments in Europe, especially those involving North Korea, are no longer distant or irrelevant.

South Korea may not be a NATO member, but it has become a consistently engaged and valued partner. In a time of shifting threats and uncertain leadership, enduring cooperation often depends less on formal treaties and more on aligned priorities and sustained trust. These ties have been shaped by political leaders, but they are increasingly embedded in institutions and shared interests. As such, the partnership between NATO and South Korea seems well-positioned to outlast individual presidencies and continue adapting to a changing global landscape.

In this story

Bence Nemeth

Bence Nemeth

Senior Lecturer in Defence Studies Education

Defence-in-Depth

Defence-in-Depth is a research feature series from the Defence Studies Department at King’s College London that analyses defence-related issues.

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