Asia Defense | Security | East Asia

What States Make of Military Exercises: Ulchi and Beyond

Repeated military cooperation can help build predictability, trust, interoperability, and institutionalized relationships among participants. 

U.S. Army soldiers advance forward during a live fire exercise as part of Ulchi Freedom Shield at Georgia Story Live Fire Complex, South Korea on Aug. 20, 2025.

Just before the South Korea-U.S. Ulchi Freedom Shield exercise began in mid-August, U.S. President Donald Trump ordered a substantial reduction in its scale. Describing the drills as “costly” and an “inappropriate and hostile” signal to North Korea – a state he termed “unthreatening and respectful” – Trump also criticized what he described as Seoul’s lack of support for U.S. operations against Iran.

Trump’s sudden decision raised concerns about South Korea-U.S. defense readiness, alliance reliability, and Washington’s wider commitment to Asia. Several analysts warned that reducing exercises could weaken deterrence and alliance coordination, while others questioned whether the move would secure reciprocal restraint from Pyongyang. Such concerns are understandable: joint military exercises are a visible manifestation of the South Korea-U.S. defense commitment, while North Korea routinely denounces them as rehearsals for war. 

The reduction alone, however, does not carry a single, self-evident political meaning. U.S. commanders have since emphasized that other combined training continues and proposed changes to its frequency and geographic distribution. How audiences interpret these changes depends on the wider pattern of cooperation, established relationships, and political context.

Scale, Scope, and Strategic Meaning 

Joint military exercises can serve two different but complementary strategic functions. They demonstrate capability and resolve to deter adversaries, but exercises also facilitate defense diplomacy. Repeated military cooperation can help build predictability, trust, interoperability, and institutionalized relationships among participants. 

Our research suggests that an exercise’s scale and scope alone cannot reliably distinguish between these functions. Deterrence and defense diplomacy often generate the same observable characteristics, making it difficult to determine where one ends and the other begins simply by examining an exercise’s material features.

Larger and more complex exercises – featuring tens of thousands of troops, sophisticated command-and-control systems, live-fire maneuvers, and complex scenarios – can demonstrate greater warfighting capability and resolve to deter. At the same time, however, those same characteristics may instead reflect years of accumulated defense cooperation and deeper levels of trust and institutional integration between the participating militaries. Their material features reveal what militaries practice and provide evidence of their capabilities but cannot by themselves establish the political messages governments intend or how different audiences will interpret them. Rather, as a political signal, joint military exercises ultimately depend on what participating states and other audiences make of them.

Different audiences will not necessarily derive the same meaning from the same exercise. Washington might intend a reduction in Ulchi as restraint toward Pyongyang, while North Korea might interpret it as a concession, Seoul as uncertainty over U.S. commitment to the bilateral alliance, and Beijing as evidence of Washington’s transactional approach to alliance management. Established relationships and political contexts are therefore essential to interpreting an exercise’s strategic meaning. 

Instead, established relationships and political contexts are more important in determining the strategic meaning of exercises than scale and scope alone. The history of Ulchi itself illustrates this. 

Ulchi’s scale and scope have seldom increased in tandem with the danger from North Korea. This divergence is significant. If Ulchi’s scale simply tracked the North Korean military threat, as one would expect for greater deterrence, participation should have risen relatively consistently alongside Pyongyang’s expanding nuclear and missile capabilities. Instead, exercise participation has repeatedly risen and fallen according to changes in the diplomatic environment. Participation declined during periods associated with the Six-Party Talks and suspended altogether to facilitate diplomacy with North Korean leader Kim Jong Un in Trump’s first term.

The scale of South Korean participation also reflects domestic politics. According to publicly available data, South Korean troop numbers were........

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