Throughout the spring of 2019, the Moon administration began hinting that it might withdraw from the General Security of Military Information Agreement (GSOMIA) that Seoul had signed with Tokyo in 2016, and in the wake of a major corruption scandal engulfing its nominee for Justice Minister, the South pulled out of the arrangement. Shortly thereafter, the ROK announced it would conduct its largest-ever military exercises around Dokdo (a set of islands also claimed by Japan, which refers to them as Takeshima).
Throughout this period of spiraling negative events, U.S. efforts to urge restraint and bring the allies together have largely taken place behind closed doors by competent but insufficiently authoritative officials. By late August 2019, this had led to a situation that threatened to undercut overall U.S. strategy. Following the South Korean withdrawal from GSOMIA, U.S. officials began speaking out more forthrightly and at a much higher level. Assistant Secretary of Defense for Indo-Pacific Security Affairs Randall Schriver, for example, clarified on August 28, that the U.S. was "not forewarned" that the Moon administration was going to withdraw from GSOMIA. Secretary of Defense Mark Esper and Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford expressed their "disappointment" at the Moon administration’s decision, as did Secretary of State Mike Pompeo, while State Department spokeswoman Morgan Ortagus Tweeted that the Moon administration’s action will "make defending #Korea more complicated and increase risk to U.S. forces." Yet to date, the most consequential figure in the U.S. government, President Trump, has declined to insert himself publicly into the issue, commenting that "it’s like a full-time job getting involved between Japan and South Korea" before adding that "if they need me, I’m there."
Indeed, when the dispute between Seoul and Tokyo initially blew up in July following Tokyo’s decision to remove South Korea from a "white list" it uses to facilitate trade, the Moon administration did request U.S. involvement, though the request was widely interpreted as Seoul requesting Washington’s help against Tokyo. At that time, Washington refused to "mediate" and instead counseled dialogue and restraint; dissatisfied, the Blue House proceeded to retaliate against Japan, including by ending GSOMIA and conducting high-profile military exercises on contested territory. When the U.S. concluded that South Korean actions were imperiling U.S. national security interests and expressed its disappointment about the Blue House’s decision to end GSOMIA, ROK Vice-Minister of Foreign Affairs Cho Se-young summoned U.S. Ambassador Harry Harris, Jr. to ask Washington to "refrain from public comments about GSOMIA."
Going forward, the U.S. seems to face three key problems in striving to encourage South Korea and Japan to return to a path focused on positive and proactive bilateral and trilateral cooperation.
First, the U.S. focus on cooperation for the purpose of countering China’s growing regional influence holds limited appeal for policymakers in South Korea. Despite China’s hostility to the U.S.-ROK alliance as revealed by unilateral economic sanctions Beijing placed on Seoul following the deployment of a Terminal High-Altitude Area Defense battery in 2017, many South Korea leaders still regard Beijing as a difficult partner whom they must nonetheless maintain cooperative ties with in order to maintain economic growth, restrain North Korea, and ultimately facilitate (or at least avoid any veto on) unification.