On December 23, 2025, the American nuclear-powered submarine USS Greeneville, a Los Angeles-class vessel, quietly slipped into the bustling port city of Busan, South Korea. The event, while not unprecedented, carried particular significance this time around, as it marked the first such visit under the administration of South Korea’s newly elected President Lee Jae-myung, who took office just six months prior in June. According to Yonhap, citing the Ministry of National Defense of the Republic of Korea, the submarine’s arrival was primarily for routine purposes: to replenish supplies and give its crew a much-needed rest. But as with many military movements in this strategically sensitive region, there was much more beneath the surface.
The USS Greeneville, with its imposing 6,300-ton displacement, stretches 110 meters in length and 10 meters in width, and is crewed by 110 sailors. Its technical specifications—reported by Yonhap and detailed by Armiya.az—underscore its formidable presence. Outfitted with high-precision Tomahawk cruise missiles, twelve vertical launch systems, and an array of torpedoes, the Greeneville is a potent reminder of the United States’ military reach and its ongoing commitment to regional security. As Yonhap noted, the vessel’s capabilities are designed not just for deterrence but for rapid response, should any threat arise on the Korean Peninsula.
This visit is the Greeneville’s fourth to South Korea, with its last stop in Busan dating back to 2016. The submarine’s arrival this December, however, follows a notable gap—while American nuclear submarines are no strangers to South Korean ports, the last such visit occurred ten months earlier, in February 2025, when the USS Alexandria docked in Busan for similar logistical reasons. According to the Ministry of National Defense, these periodic visits are coordinated to ensure the operational readiness of US naval forces in the region and to reinforce the military partnership with South Korea.
In the words of a Yonhap report, "The Navy of the Republic of Korea stated that the US Navy’s nuclear submarine USS Greeneville, with a displacement of 6,300 tons, entered the port of Busan Naval Base on December 23 to replenish supplies and allow the crew to rest." The arrival was also intended to foster military cooperation, with South Korean officials planning to exchange experience with their American counterparts, thereby "further strengthening joint combat readiness."
The timing of the Greeneville’s visit is noteworthy. President Lee Jae-myung’s administration, still in its early days, has emphasized the importance of maintaining robust defense ties with the United States amid ongoing tensions with North Korea. The arrival of a nuclear submarine, especially one as capable as the Greeneville, sends a clear signal of deterrence and solidarity. According to Yonhap, the Ministry of National Defense of the Republic of Korea confirmed that the visit was part of broader efforts to check the readiness of US Navy forces to respond to any threat.
Yet, not everyone in the region views these port calls with equanimity. North Korea has consistently criticized the presence of American nuclear submarines in South Korean ports, viewing such visits as provocative and destabilizing. This sentiment was echoed in several reports, with North Korean officials issuing statements condemning the arrival of the Greeneville and warning of heightened tensions on the peninsula. While these criticisms are not new, they highlight the delicate balance that South Korea and the United States must maintain as they navigate their security alliance in a region marked by historical grievances and persistent threats.
For the United States, the deployment of nuclear submarines like the Greeneville serves multiple purposes. Beyond the immediate logistical needs of resupply and crew rest, these visits are a tangible demonstration of America’s commitment to its allies. The presence of such a powerful vessel in Busan is meant to reassure South Korean officials and the public that the US remains steadfast in its security guarantees, especially in light of North Korea’s ongoing missile and nuclear development programs.
According to Armiya.az, the Greeneville’s arrival also provided an opportunity for joint military exercises and exchanges, with South Korean and American forces planning to share tactics and operational insights. This kind of collaboration is seen as essential for maintaining the interoperability of the two nations’ armed forces—a key factor in ensuring that, should a crisis arise, both sides can respond quickly and effectively.
Looking back, the pattern of American submarine visits to South Korea reflects the ebb and flow of regional tensions. The last visit by the Greeneville in 2016 came at a time of heightened concern over North Korea’s nuclear ambitions. More recently, the February 2025 visit by the USS Alexandria occurred against a backdrop of renewed missile tests by Pyongyang. Each time, the arrival of a US nuclear submarine has been both a practical step and a symbolic gesture—a reminder to allies and adversaries alike of the enduring US presence in East Asia.
Interestingly, sources in the Ministry of National Defense of the Republic of Korea indicated that the Greeneville’s visit would soon be followed by the arrival of a US Navy surface ship, further underscoring the ongoing military cooperation between the two countries. This pattern of alternating submarine and surface vessel visits is designed to maintain a continuous US naval presence in the region, providing both reassurance and deterrence.
As the Greeneville’s crew enjoys some well-deserved shore leave and the submarine takes on fresh supplies, the broader implications of its visit are not lost on observers. For South Korea, the presence of a US nuclear submarine is both a shield and a signal—a shield against potential aggression from the North, and a signal to the world that the US-South Korea alliance remains strong. For North Korea, it is a reminder of the formidable military power arrayed against it, and a source of ongoing frustration and concern.
In the months ahead, as President Lee Jae-myung’s administration settles into its role, the dynamics of the US-South Korea alliance will continue to evolve. But for now, the arrival of the USS Greeneville in Busan stands as a vivid illustration of the enduring ties between the two countries—and the complex, sometimes fraught, security environment in which they operate.
Ultimately, while the Greeneville’s visit was, on the surface, a routine stop for supplies and rest, it also served as a timely reminder of the strategic realities shaping Northeast Asia. In a region where history, politics, and military power intersect, even the most routine port call can carry outsized meaning.
