The US-Japan and US-ROK alliances are, and for decades have been, a cornerstone of Asia-Pacific security, helping to maintain regional stability while allowing Japan and Korea to focus on economic development. A key part of the US relationship with each country is extended deterrence. Through legal and political obligations, the United States says that an attack on either ally will be treated as an attack on the United States and met with an appropriate military response, possibly even with nuclear weapons. For the United States, the key challenge is ensuring that allies are sufficiently assured without unnecessarily provoking potential adversaries.

At the Track II level, the Pacific Forum CSIS has worked to find ways for the United States to correctly tailor its assurance of Japan and South Korea. Over the last several years, the Pacific Forum CSIS has hosted separate bilateral US-Japan and US-ROK strategic dialogues, which have explored respective threat perceptions, strategic priorities, and defense policies. These Track II exchanges have helped to reduce misunderstanding, both among the participants and in their respective governments. Indeed, they set the groundwork for the Track I extended deterrence dialogues that the United States established with Japan and South Korea in 2010.

The Pacific Forum CSIS has also prided itself on including the next generation in these discussions. As part of the Young Leaders (YLs) program, young professionals have been able to observe and participate in both the US-Japan and the US-ROK strategic dialogues. Their participation provides two primary benefits. First, they offer a unique perspective that often contrasts with senior participants whose views are clouded by the Cold War. Second, they interact with and learn from senior participants, gleaning insight from their experience and expertise.

Official and unofficial bilateral dialogues have allowed the United States and its respective allies to make great strides in aligning expectations and policies but work remains. US interests in Northeast Asia require Washington to encourage its allies to participate in trilateral cooperation. Facing a stronger, more assertive China and a more provocative, less predictable North Korea, security and foreign policy professionals in the three countries recognize the importance of greater trilateral security cooperation. Yet, they remain dissatisfied because serious political and emotional hurdles remain.

Recognizing the importance of Northeast Asian trilateralism and the obstacles that remain, the Pacific Forum CSIS with support from the Project on Advanced Systems and Concepts for Countering WMD (PASCC) and the Defense Threat Reduction Agency (DTRA) in 2013 established a US-ROK-Japan Extended Deterrence Trilateral Dialogue. The meetings have brought together experts and officials to explore the benefits of trilateral cooperation, the obstacles that remain, and potential strategies for improving Japan-Korea relations.

In addition to substantive dialogue, the participants at the most recent meeting, which took place in Maui on July 23-24, 2014, took part in a two-stage tabletop exercise (TTX), which was designed to test how each of the three countries would respond to a gray zone provocation by North Korea. Stage one began with North Korea sinking a Japanese vessel amid increased tensions on the Korean Peninsula. Stage two started with a US- Japan retaliatory strike against a North Korean naval base, followed by a North Korean artillery barrage against isolated South Korean farmland (with several civilian casualties) and a North Korean nuclear detonation over the Sea of Japan/East Sea (with no casualties). In each stage, teams of US, Japan, and ROK nationals conferred and offered recommendations for how their country should respond.

As in the bilateral discussions, the US-Japan-ROK dialogues also included next- generation participants. 17 Pacific Forum YLs observed the discussions and then participated in the TTX. Rather than being divided into country groups, the YLs formed a single team that recommended actions for all three governments in each stage of the exercise. The YL team functioned as a control group whose recommendations could be compared to senior participants to identify generational differences. On many issues the perspectives of the generations converged, but, in general, the senior teams were primarily focused on the need to re-establish deterrence by moving up the escalation ladder, while the YL team was relatively more concerned by the risk of escalation.

The Maui TTX was a success and offered important insights about the challenges and opportunities for trilateral cooperation in a potential crisis. It also showed the benefits that TTXs provide to next generation participants, challenging them to think through a difficult situation and adopt the perspective of government decision makers. As a result, the Pacific Forum encouraged the YLs who participated in the exercise to design their own crisis scenario, which would be run at a future YL event. In the weeks after the meeting, teams of YLs designed their own US-Japan-ROK crisis scenario and wrote background guides for the respective country teams.

Four months later, the Pacific Forum CSIS with support from the SKC Corporation held the 1st US-ROK-Japan Young Leaders Dialogue on November 12-14, 2014 in Seoul. Approximately 35 US, ROK, and Japanese next-generation experts and select senior advisers joined a two-day discussion of the ROK-Japan bilateral relationship and the US- ROK-Japan trilateral relationship. The conference also featured the table-top exercise that was designed by YLs who attended the senior-level dialogue in Maui.