The inaugural U.S.-Japan-South Korea trilateral summit will yield defense and intelligence arrangements to confront security challenges in Northeast Asia, but its main purpose is to institutionalize a relationship fraught with historical baggage and future uncertainty. On Aug. 18, U.S. President Joe Biden, South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida will convene at the U.S. presidential retreat Camp David for what will be the first-ever dedicated summit between their three countries. The meeting will focus on deepening military and intelligence collaboration between the United States, Japan and South Korea, while also undertaking a broader scope with respect to economic security, emerging technologies and non-government diplomacy (such as among business and academic leaders). Japan and South Korea remain unlikely to accede to a trilateral pact that would require them to come to each other's defense in the event of an attack. But the three countries' current leaders will probably still ink defense and intelligence agreements that aim to prevent their successors from derailing future cooperation by institutionally entrenching the trilateral partnership.

• The United States hopes the trilateral summit format will become an annual occurrence, with U.S. Secretary of State Antony Blinken hailing the event as ushering in a ''new era'' in U.S.-Japan-South Korea ties. South Korean President Yoon similarly referred to the meeting as a means to ''set a new milestone in trilateral cooperation.''

The summit follows recent confidence-building measures between Japan and South Korea that are bringing the two traditional rivals together amid changing geopolitical realities. All three governments are intent on seizing the geopolitical moment to achieve rapprochement between Japan and South Korea in order to more readily respond to rising threats from China, Russia and North Korea. The United States already has defense treaties with Japan and South Korea. Its strategy to contain China in the East China Sea requires that Tokyo and Seoul set aside their grievances and deepen their bilateral cooperation without the need for the White House to mediate. Japan's main concern is China's growing assertiveness (especially toward Taiwan), though North Korea poses an additional threat. Protecting Taiwan and deterring a Chinese invasion is key to Japanese security doctrine, which bolstered security relations with neighboring South Korea could help accomplish. Japan's territorial waters have also been increasingly subject to nearby joint Chinese-Russian naval drills, a posture Tokyo deems threatening. For South Korea, rapprochement with Japan has been front and center of the Yoon administration's agenda as well. A closer relationship with Tokyo (particularly in the realm of intelligence sharing) would enable Seoul to pursue a more hawkish approach to North Korea's saber-rattling in the form of missile tests. Amid the escalating U.S.-China rivalry, increased coordination with Japan would also enable South Korea to hedge against being forced to choose between its main economic partner (China) and its main security partner (the United States). This necessitates a stronger economic relationship with the United States to compensate for veering away from China. In addition, the Yoon administration wants to ensure that South Korea does not become a U.S. strategic afterthought in the region, as Japan's emergence from self-imposed pacifism immediately renders it the primary strategic counterweight to China. Russian military activity around the Korean Peninsula is also a concern for Seoul, as evidenced by the June 6 incursion of Chinese and Russian fighters into South Korea's air defense identification zone.

• Tensions between Japan and South Korea are rooted in the former's 1910-1945 occupation of the Korean Peninsula in which the civilian population suffered human rights abuses. The legacy of the occupation continues to plague the two countries' modern-day relationship — particularly around the issue of South Korean ''comfort women,'' who the Japanese army used as sex slaves during World War II, and compensation for forced labor. 
• Prior confidence-building and institutionalization efforts include a joint trilateral statement on the Indo-Pacific partnership that U.S., South Korean and Japanese officials issued in November. Yoon also visited Japan in March (marking the two countries' first bilateral summit in 12 years), while Kishida traveled to South Korea in May for a follow-up visit. Earlier this year, South Korea and Japan mutually restored each other to their respective ''white lists'' of trade partners as well, ending a four-year dispute. In addition, the United States, Japan and South Korea met at the Shangri-La Summit in Singapore in early June where they agreed to flesh out a real-time intelligence-sharing arrangement before the end of the year. 

The summit is primarily aimed at anchoring the trilateral relationship in a permanent structure that cannot easily be undone by future administrations, though it will also produce immediate deliverables in defense and security. According to both senior U.S. and South Korean officials, the summit will likely yield two documents: the Camp David Principles (which will lay out commitments) and the Spirit of Camp David (which will lay out the three countries' collective vision for the region). With the aim of establishing protocols for managing the trilateral relationship, these documents will contain aspirational measures on harmonized economic norms, technology sharing, combating climate change, prioritizing nuclear non–proliferation, countering economic coercion from China and building supply chain resiliency. They will likely also establish trilateral consultative bodies (e.g. a crisis hotline and/or a mechanism for joint military drills) and seek to further enhance maritime collaboration (such as on port infrastructure, shipping efficiencies and customs procedures, search and rescue operations, fisheries, and environmental conservation). The documents will probably aim to forward the aforementioned real-time trilateral intelligence-sharing mechanism as well — something particularly helpful with respect to early warning systems for ballistic missiles (as opposed to delayed intelligence, which is the current situation). By providing a sense of urgency, the risk that future governments in each country may reverse these initiatives is driving current U.S., South Korean and Japanese leaders to enshrine the partnership in as thorough terminology as is actionable. To that end, the summit will likely center around the newly instituted protocols and frameworks to govern the relationship.

• The U.S-Japan-South Korea summit is highly unlikely to yield a deal with language analogous to the Article 5 protections enshrined within NATO's founding treaty, which requires members of the Western security alliance to defend each other in the event of an attack. But China has nonetheless slammed the upcoming Camp David summit as the initiation of a ''mini-NATO'' in Asia. With China's threat perception rising, it will likely pursue deeper security ties with Russia's Pacific fleet and far-eastern forces and conduct additional exercises in the area akin to July's joint drills in the Sea of Japan.
• North Korea may also conduct retaliatory actions in response to the upcoming Camp David summit, with South Korea's intelligence agency telling lawmakers on Aug. 16 that Pyongyang could test another intercontinental ballistic missile and launch a spy satellite to demonstrate its displeasure with the trilateral meeting.
• Political developments in the three countries could derail cooperation in the future — particularly in the United States and South Korea, which both have increasingly polarized electorates. South Korea's opposition Democratic Party opposes rapprochement with Japan and could thus derail that process if the party retakes control of the presidency in 2026. In the United States, the potential reelection of former U.S. President Donald Trump in 2024 could similarly see the White House deprioritize the Korean Peninsula and turn away from the Camp David agreements. Japan, for its part, is the most likely to remain consistent in its approach but is skeptical of the turbulent political environments in the United States and South Korea. Should it appear the trilateral framework is losing momentum, Japan may have to pursue partnerships with other countries.