Cai Cuihong and Li Yuhua,“An Analysis of Cybersecurity Cooperation in the QUAD Mechanism”,Contemporary International Relations,No.5,2024,pp.24-42 Abstract: The Quadrilateral Security Dialogue (QUAD) is an informal international dialogue mechanismled by the United States, with Japan, India and Australia as members. With the launch and promotion of the United States’ “Indo–Pacific strategy,” this mechanism has been revitalizedand strengthened, and cybersecurity has been given high priority by the QUAD among the many issues for cooperation. The QUAD has made remarkable progress in strengthening itscybersecurity cooperation in terms of the level of cooperation, the structure of cooperation and the areas of cooperation. This strengthening is mainly driven by the strong push of theUnited States based on its strategic competition with China, the environment of the anarchic governance of cyberspace, and the initiatives of the allies to cater to the quadrilateral moves. The strengthening of cybersecurity cooperation under the QUAD has not only undermined China’s development interests and national security, but also affected the “Indo–Pacific” region and the international security situation, and hindered the current process of global cyberspace governance. At the same time, however, the future of QUAD cybersecurity cooperation is also plagued by the divergence of the parties’ willingness to cooperate and concerns about their interests, differences in the level of cyber development, and the degree of the allies’ trust in the United States. Keywords: QUAD, cybersecurity, “Indo–Pacific strategy”, US–China relations