The first reporting period of 2024 US-Korea relations was busy, both with managing ongoing issues (good and bad) and adapting to genuinely new evolutionary turns in US-Korea affairs. Concerning the former, US-South Korea relations continued on the same trajectory since President Yoon Suk Yeol assumed office in 2022: deepening bilateral alliance interoperability, enriching trilateral cooperation with Japan, increasing economic security policy convergence with the US. And this despite new foreign, defense, finance, and trade ministers in Seoul. Widely viewed as a referendum on Yoon, April National Assembly elections cast a shadow over much of his foreign and security policy during the reporting period. However, the crushing defeat of Yoon’s conservative People Power Party is unlikely to affect his approach to external affairs, where the president retains significant unilateral power. The “management” bucket also contains more threatening scenarios that have been building for months, years, decades. At the top of the list in importance is North Korea’s build-out of its nuclear and missile program, which continued apace in the January-April 2024 period, also providing more evidence of the essential hopelessness of international sanctions.

There are many metaphors about using propitious moments to prepare for an inclement future: make hay while the sun shines, the best time to fix the roof is on a clear day, strike while the iron is hot, etc. These all imply the drudgery of work: a farmer baling hay on a sunny day, a slater shingling high on a roof under a blue sky, a forger hammering inside a sweltering workshop on a breezy afternoon. In a third semester continuation of the rest of a tense, yet stable 2023, there is a sense in which both South Korea and North Korea have been following the lesson of these proverbs as they use relative calm on the Korean Peninsula to build out their respective, opposed security and defense capabilities. Another, similar proverb captures an additional element of this dynamic: if you spend your whole life waiting for the storm, you’ll never enjoy the sunshine. Despite the tension on the Korean Peninsula, leaders in both Seoul and Pyongyang appear confident, even buoyant about their security and defense buildups.

The May-August 2023 reporting period saw further divergence between Washington’s relations with Seoul and Pyongyang. This dynamic was an acceleration of a trend already evinced at the April Joe Biden-Yoon Suk-yeol summit that produced the Washington Declaration modernizing US-South Korea extended deterrence, and the alliance as a whole. Washington-Seoul bonhomie contrasts manifestly with Washington-Pyongyang relations, whose level of hostility remains the same as four months ago, 14 months ago, or 24 months ago. That is, all the positive action during summer 2023 came from the continued dramatic growth in the US-South Korea alliance, notably via the extraordinary formation of a genuine trilateral US-South Korea-Japan quasi-alliance. This development has been in the works for the last 18-24 months, was given momentum by improving South Korea-Japan government relations and a Yoon-Kishida summit in May, and was concretely founded in August at the US-South Korea-Japan summit at Camp David.

South Korean president Yoon Suk-yeol has tried to make a priority of transforming the traditional US-South Korea military alliance into a “global, comprehensive strategic alliance” with increasing ambitions beyond hard security issues on the Korean Peninsula and in Northeast Asia in general. Yoon and his foreign policy team get an “A” for vision and effort—joining the NATO Asia-Pacific Four (AP4) and releasing an Indo-Pacific Strategy in 2022 are evidence. But, like Michael Corleone trying to go legit in The Godfather III, every time they make progress getting out, they get pulled back into the Peninsula. To wit, during the first trimester of 2023 Korean Peninsula security issues again commanded disproportionate attention from Seoul and Washington. The proximate cause for this dynamic is North Korea’s mafioso-in-chief, Kim Jong Un, who started 2023 with a January 1 missile launch and kept at it throughout the winter. This, of course, followed record-breaking 2022 North Korean missile tests and demonstrations, which totaled approximately 70 launches of around 100 projectiles. Given the near-zero prospects for North Korean denuclearization and the growing arsenal at Pyongyang’s disposal, it is understandable that any South Korean president would be distracted from interests further afield.

Continuing a trend from the May-August reporting period, the final reporting period of 2022 in US-Korea relations was marked by an accelerated ratcheting up of tension. In short, numerous problems reared up on the Korean Peninsula from September-December, and good solutions have been few. And not only does this describe relations between the US and North Korea, but in their own, friendly way also the situation between Washington and Seoul, whose frequent invocations of rock-solid alliance cooperation belie unease about crucial areas of partnership.

Two critical issues have been increasingly affecting the US-South Korea alliance in 2022, with the September-December period no exception. First, South Korea desires ever more alliance-partner defense and security reassurance from the US in the face of a growing North Korean nuclear threat and Chinese revisionism. Yet the US has downward-trending limits on credible reassurance as North Korea masters nuclear weapons technology that threatens US extended nuclear deterrence for South Korea. The US also faces less geopolitical pressure to effusively reassure its Indo-Pacific allies—including South Korea—as China grows to menace the regional order and the US consequently faces lower risk of ally hedging or realignment.

Lopsided: such was the state of US relations with the two Koreas during May-August 2022. The Washington-Seoul axis mostly flourished on the military/security, diplomatic, economic, and cultural fronts, while Washington and Pyongyang deepened doldrums whose depths had been plumbed in prior reporting periods. For the former, the most significant items included the May inauguration of conservative South Korean President Yoon Suk Yeol and quick follow-on summit with US President Joe Biden, increasing trilateral US-South Korea-Japan cooperation, a raft of announcements on US-South Korea economic and technology cooperation, the resumption of field maneuvers in US-South Korea joint military exercises, and South Korea’s continuing growth as a serious middle power player in foreign policy, including stepped-up engagement with NATO. In US-North Korea relations, a COVID-19 outbreak failed to lead the Kim Jung Un regime to open up to outside humanitarian assistance, as Pyongyang remained content to keep borders mostly closed and allow the virus to course through the population with only basic prophylactic measures. On the positive side, Pyongyang’s hyperactive missile testing in spring slowed during summer, and a feared (yet still expected) seventh nuclear test failed to materialize.

Winter/Spring 2022 was a dynamic, clarifying time in US-Korea relations, following repetitious, turbid reporting periods in 2021. South Korea geared up for and held a presidential election, won with a razor-thin margin by conservative Yoon Suk-yeol. His new administration, replacing the progressive government of term-limited Moon Jae-in, promises to place very different accents on the US-South Korea alliance and inter-Korean relations. Washington is relieved to see Yoon assume office, as US senior leadership, policymakers, and alliance managers are comfortable with his foreign and security/defense policy team. Moon and his progressives did plenty to advance the US-South Korea alliance, but their parochial, Peninsula-focused diplomacy was occasionally a source of friction and often seemingly quixotic vis-à-vis North Korea. The Yoon administration is poised to attempt to make the US-South Korea alliance more comprehensive geographically and functionally, although conservative administrations also pose their own idiosyncratic risks to the US-ROK alliance. For its part, North Korea embarked on an unprecedented missile launch spree during the January-April 2022 reporting period, with 13 separate tests or demonstrations (with three more to follow so far in May) of a variety of known and new systems ranging from short-range ballistic missiles (SRBMs) to hypersonic weapons to (supposedly) the previously untested Hwasong-17 intercontinental ballistic missile (ICBM). Three more missile tests followed in May. North Korean supreme leader Kim Jong Un subtly clarified that Pyongyang’s nuclear posture is not totally deterrence-focused, but includes warfighting use, underscoring the likelihood the regime develops tactical nuclear weapons. This would also likely mean a seventh nuclear test. Pyongyang’s provocations and fiery rhetoric were leavened with celebration, as April parades in North Korea marked the 110^th Day of the Sun (the birthday of Kim Il Sung) and the 90^th anniversary of the foundation of the Korean People’s Army (KPA). These events have a primarily domestic focus, but they also serve as international propaganda, announcing outwardly that North Korea is strong and united. This attempt at perception management will be tested by reality, as an outbreak of omicron variant COVID-19 in early May represents a serious risk for North Korea.

Looming in the background of these events was the Russia-Ukraine war, which has current and future implications for US relations with the Koreas. South Korea slowly but surely supported US-led sanctions on Russia, while North Korea predictably blamed the US for the conflict. Going forward, Washington’s likely increasing pressure on Moscow will be a litmus test for Seoul’s willingness to work comprehensively with its alliance partner on maintaining the international rules-based order; that same pressure campaign will also open up possibilities for greater Pyongyang-Moscow cooperation, notably in sanctions evasion.

The final four months of 2021 US-Korea relations played out largely as anticipated: the US deprioritized creative outreach to North Korea and generally subordinated the Korean Peninsula (both South and North) to the US-China rivalry. North Korea was considered likely to continue its self-imposed isolation while advancing its nuclear and missile arsenal. And it was expected that South Korea would doggedly pursue inter-Korean diplomacy while building up its military capabilities, optimizing a calibrated approach to the US and China, and bracing for a period of political opacity leading up to the March 2022 presidential election. Standard set-pieces were also evident during the September-December reporting period: US and South Korean officials did the yeoman’s work of alliance management via frequent meetings and periodic performative statements of alliance cohesion. North Korea celebrated National Foundation Day and the anniversary of the Worker’s Party of Korea, and held an end-of-year party plenum. South Korean President Moon Jae-in used his UN General Assembly speech to encourage international support for inter-Korean reconciliation.

The third trimester of 2021 did have some surprises, however. The Moon administration’s full-court press for a declaration of the end of Korean War was out of step with US and North Korean priorities. Announcement of the AUKUS (Australia-UK-US) strategic pact caught all off-guard, including Seoul, which has jealously eyed Washington’s decision to work with Canberra on a nuclear-propelled attack submarine. US insistence on ensuring that South Korea’s technology industry comports with US geostrategic aims vis-à-vis China was more strongly visible—and friction-inducing—than expected. And Squid Game rocketed from obscurity to global sensation, proving that BTS does not have a monopoly on South Korea’s cultural exports.