SEPTEMBER 2025
Mutual Defense in Cyberspace
Joint Action on Attribution
By: Julia V. Brock and James A. Lewis
O
n the seventieth anniversary of the U.S.-Republic of Korea (ROK) alliance, the leaders of the two
countries declared that the Mutual Defense Treaty applies to cyberspace. The United States
and South Korea agreed to expand the scope of the agreement and promote cooperation in
cybersecurity technologies, policies, and strategies, including cyber threat information sharing.
The United States and the ROK have signicantly strengthened their cybersecurity cooperation in recent
years. South Korea’s membership in NATO’s Cooperative Cyber Defense Centre of Excellence laid the
groundwork for enhanced information sharing, joint exercises, and the development of shared standards.
The U.S.-ROK Cybersecurity Working Group, established in 2022, has focused on strengthening
mechanisms for collaboration and joint defense, as well as defensive strategies. Both countries have
also emphasized the importance of international partnerships in addressing cyber threats posed by
authoritarian states. The U.S.-ROK Strategic Cybersecurity Cooperation Framework, signed in April 2023,
further solidied this commitment by increasing information sharing and joint response eorts.
Washington and Seoul are actively engaged in countering cyber threats, particularly those from
the Democratic People’s Republic of Korea (DPRK). The Counter Ransomware Initiative (CRI), the
U.S.-ROKJapan Trilateral Summit, and the ROK’s 2024 National Cybersecurity Stratey each highlight
the shared goal of disrupting the DPRK’s malicious cyber activities and protecting critical infrastructure.
Recent memoranda of understanding (MOUs) between the United States and the ROK have further
strengthened cooperation in areas such as computer emergency response team communications and
supply chain resilience.
Current Cooperation Structures
The overarching structure for the U.S.-ROK alliance is the 2023 Strategic Cooperation and
Coordination Framework (SCCF). The SCCF provides a diplomatic mechanism to facilitate discussions
between the two countries on a range of issues, particularly those concerning security, military
cooperation, and regional challenges. The SCCF aims to enhance bilateral coordination, improve
