The U.S.-ROK alliance faced a quickening pace of North Korean provocations in 2016-17, with Pyongyang violating UN Security Council resolutions dozens of times. Those violations included a fourth nuclear test in January 2016, fifth in September 2016, and sixth in September 2017, as well as numerous missile tests of various trajectories from different platforms. North Korea tested intermediate-range missiles overflying Japan and missiles of intercontinental range on lofted trajectories, while developing road-mobile and submarinelaunched ballistic missiles. As policymakers in Seoul and Washington coordinated responses to those provocations, changes in national leadership and domestic political preferences brought into question the bilateral trust the alliance needs to deter conflict, reassure publics, and promote regional cooperation.

Elections have consequences, even before votes are cast. Enduring international security alliances are based on shared national interests and a track record of diplomatic commitments and military cooperation. For allies with highly integrated defense policies, such as the United States and South Korea, it is natural for policymakers and citizens to keenly observe the national elections of the other country. Will the next government be a reliable partner, or will it fail to honor existing agreements? Will the incoming leadership improve relations, or will it downgrade cooperation? These questions were being asked before Donald Trump and Moon Jae-in were elected. The search for answers inevitably involves speculation, feeding expectations that are often overly optimistic or pessimistic.

Ahead of Trump’s election, his campaign rhetoric questioned the terms and intrinsic value of the alliance to an extent not seen since Jimmy Carter’s 1976 campaign promise to withdraw U.S. troops from the Korean Peninsula. President Moon came to power on the heels of conservative president Park Geun-hye’s impeachment and removal for corruption. Moon’s politics are notably more progressive than Park’s or Trump’s, including a record of pro-engagement policies toward North Korea. Against this backdrop, Kim Jong-un delivered his 2018 New Year’s Day address claiming that North Korea has the ability to hit any U.S. city with a nuclear-armed missile, but that Pyongyang is ready to re-engage Seoul via participation in the Winter Olympics.