Alex Soohoon Lee argues that security cooperation between the ROK, United States, and Japan is a key Indo-Pacific security framework given that the three countries represent one-third of the world economy and are among the top ten military powers. Lee first examines the historical context of trilateral security cooperation, before examining the commitments made at the Camp David Summit and highlighting progress made since that historic meeting while acknowledging challenges moving forward. Lee contends that President Yoon’s efforts to normalize relations with Japan and emphasize ROK-US-Japan linkages have contributed to progress. Yoon and Japanese Prime Minister Fumio Kishida emphasized cooperation in 2023, while Yoon and President Biden have underscored the importance of trilateral security cooperation since their first meeting in 2022. Although the leaders may have differing levels of motivation and preferred directions of cooperation, Lee argues that they should concentrate on the traditional agenda of security on the Korean Peninsula, with an emphasis on building sustainability into such cooperation. In order to ensure the longevity of trilateral cooperation, Lee contends that it is crucial to establish institutionalized structures and learn from past experiences. While exploring and developing new agendas remains important, Lee posits that sustainability must be prioritized to give emerging efforts real meaning. To achieve sustainability, a ROK-US-Japan Cooperation Secretariat should be created to maintain ongoing cooperation. Ultimately, sustaining the legacy of Camp David will be critical to maintaining peace and prosperity in the Korean Peninsula and Indo-Pacific region.