The 2016 elections of US President Donald Trump and ROK President Moon Jae-in provide a unique opportunity to assess the state of the US-ROK alliance. To promote a better understanding of areas of conflict and opportunities for cooperation, the Northeast Asian History Foundation (NAHF) and the Pacific Forum convened in June 2017 the second iteration of a workshop on the interplay of historical and current events in the US-ROK bilateral relationship. Participants discussed changing political dynamics in each country, the significance of populist and nationalist movements, and the impact of those trends and the broader Northeast Asia security environment on the US-ROK alliance. While there are good reasons to be confident, there are equal if not more compelling reasons to be concerned. As always, alliance management is a must.

The political forces that brought about the rise of Trump and Moon are, on the surface, similar. Both tapped into voters’ discontent with the status quo, whether it be disillusionment in the aftermath of Park Geun-hye’s corruption scandals or the economic discontent of voters in the US who felt they were ignored by the political elite. But these political forces led to very different results – a conservative in the White House and a progressive in the Blue House – and those differences could produce conflict, particularly in regard to North Korea policy.

Mixed messages from both administrations have led to some uncertainty and diminishing confidence; a divergence in policies in Washington and Seoul could undermine efforts to denuclearize the Korean Peninsula. Skillful diplomacy is needed to keep both countries moving in the same direction. Public opinion may make this difficult, however, as anti-North Korean sentiment has been growing in the US while progressives in the ROK may call for increased engagement.

Populist movements in both countries have increased nationalism, but that phenomenon must be apprised accurately. In the United States, populism has assumed protectionist characteristics and created uncertainty about international commitments, while in Korea it has not taken on anti-US characteristics. Within the US-ROK context, ROK nationalism aims at greater autonomy within the security partnership. There is, however, concern about South Korean nationalism in regard to Japan: it is unclear if the Moon administration will seek short-term political gains by playing on this sentiment or will work instead to preserve the ROK-Japan relationship.

While there are points of friction, shared interests and the constraints of a security crisis on the Korean Peninsula leave the alliance “fundamentally strong.” As always, however, more work needs to be done if the alliance is to continue to serve each country in a changing security environment. Questions over Japanese rearmament, China’s regional rise, North Korea’s progress toward a working nuclear weapon, and the Trump administration’s Asia policy have taken on increased visibility in 2017.

While there is reason to be confident about the US-ROK alliance in the event of a crisis on the Korean Peninsula, it is much more difficult to make assumptions once focus shifts to broader issues – for example, China’s efforts to re-establish itself as a regional power. The South Korean mindset of “a shrimp among whales” can serve as an excuse for inaction and reduce Seoul’s leverage when negotiating with Beijing. In this regard, the deployment of THAAD has proven to be a useful case study. Participants generally agreed, however, on a preference for a strong China over a weak China or, as one ROK participant suggested, “a strong but not an assertive China.”

Domestic constraints may lead to additional challenges. Uncertainty over the Trump administration’s willingness to commit political and financial resources to maintain US commitments in Asia, questions over alliance burden-sharing and calls in the ROK to develop indigenous defense capabilities, and a generational shift in the ROK away from unification as an end goal could breed tensions.

The US-ROK alliance is vital to the security of the Asia Pacific, and while its foundation remains strong, core issues can prove destabilizing if not managed correctly. It is more important than ever for policymakers and advocates to promote an accurate understanding across borders and to communicate the importance of the alliance to their respective publics.