Confrontation between the U.S. and China over the Yellow Sea: A New Phase in East Asian Security Indicated by the Strategic Role Shift of U.S. Forces in South Korea

On February 18, 2026, up to 10 F-16 fighter jets from the United States Forces Korea (USFK) took off from Osan Air Base in Pyeongtaek, Gyeonggi Province, and flew in international airspace over the Yellow Sea, prompting an emergency scramble of Chinese military aircraft. While this incident may appear to be part of routine military exercises at first glance, it is, in fact, a significant event symbolizing a fundamental change in the security structure of Northeast Asia.

The F-16s from USFK flew in international airspace between South Korea's Air Defense Identification Zone (KADIZ) and China's Air Defense Identification Zone (CADIZ). There were no reports of violations of the air defense identification zones, and both pilots maintained a professional distance; however, the Chinese side immediately scrambled fighter jets in response to the US military aircraft flying near CADIZ. This rapid response highlights Beijing's extremely high alertness regarding air operations near its defense boundary, even if ADIZ is not recognized as sovereign airspace under international law.

When asked about the incident, a South Korean Ministry of National Defense official stated, "The South Korean military and USFK maintain a strong combined defense posture," and added, "We cannot confirm." This dual expression reflects Seoul's cautious diplomatic balancing act, reaffirming the strength of deterrence while refraining from commenting on operational transparency. According to military sources, USFK had notified the South Korean military in advance about the exercise itself, but did not provide detailed information, including its purpose. After grasping the full scope of the incident, the South Korean military conveyed its concerns to the US side.

The confrontation over the Yellow Sea should not be understood as a one-off tactical event but rather in a broader context. USFK Commander General Xavier Brunson stated in November 2025, "The forces already stationed on the Korean Peninsula are not those that require distant assets that the US must break through during crises or emergencies, but rather forces that are already positioned within the bubble boundary." This statement has taken on even greater significance in light of the latest confrontation in the Yellow Sea.

General Brunson's "bubble internal" theory suggests a fundamental redefinition of the strategic role of USFK. Traditionally, the primary mission of USFK has focused on deterring the North Korean threat; however, since the start of President Trump's second term, Washington officials have suggested that USFK would take on a larger role in deterring China, while South Korea would assume more responsibility for responding to the North Korean threat. The latest National Defense Strategy released by the US Department of Defense in January 2026 explicitly states, "South Korea has the capability to take primary responsibility for North Korean deterrence with important but more limited US support."

The operation on February 18 is a practical manifestation of this policy shift. It is extremely unusual for USFK to conduct large-scale exercises over the Yellow Sea unilaterally outside of regular joint exercise periods with the South Korean military. Operations near China's ADIZ were clearly directed at Beijing. Zhao Hanfan, chief researcher at the National Unification Research Institute, described this incident as "the first visible sign that USFK is shifting its role toward countering China."

The geopolitical importance of the Yellow Sea derives from its proximity to China's major coastal provinces, South Korea's capital region, and critical maritime transport routes. This maritime area has transformed into an operational space where surveillance flights, naval deployments, and air patrols serve both deterrent and signaling functions. For the US, the presence of USFK in South Korea is central to its Indo-Pacific strategy, historically focused on deterring North Korean aggression, but is now being recalibrated to address broader regional emergencies, including potential crises involving China.

China's response is also noteworthy. On February 21, the Chinese state-run Global Times reported that the People's Liberation Army organized naval and air forces to "conduct continuous monitoring and vigilance throughout the entire process, effectively handling the situation in response to US military activities over the Yellow Sea." The fact that Beijing did not immediately issue a formal protest after the incident may indicate a restrained response, but this restraint itself functions as a strategic signal, reflecting a judgment that a controlled response contributes more to long-term deterrence messaging than overt escalation.

This confrontation also exposed structural tensions within the US-South Korea alliance. South Korea's trade dependence on China has reached about 25%, significantly exceeding its 13% dependence on the US. This economic interdependence is increasingly integrated into a security alliance framework that aspires to counter China's military assertions. Seoul's concerns do not necessarily imply opposition to US operations but highlight the strategic necessity to avoid being drawn into an escalation cycle that exceeds immediate deterrence requirements against North Korea.

The historical context is also important. The February 2026 confrontation can be situated within the historical continuity of US-China aerial encounters in the Yellow Sea and surrounding waters. In October 1994, the US aircraft carrier Kitty Hawk encountered a Chinese Han-class nuclear submarine in the Yellow Sea, leading to several days of tracking and emergency scrambles of fighter jets. In May 2017, two Chinese Su-30 fighters intercepted a US Air Force WC-135 aircraft over the Yellow Sea, with one of the Chinese jets performing a barrel roll over the US aircraft. In the same month, a Chinese J-10 fighter approached a US P-3 surveillance aircraft within a few hundred feet.

The US Department of Defense's report from October 2023 recorded over 180 dangerous aerial intercepts by Chinese pilots in the past two years, including tactics considered violations of aviation norms, such as close passes and flare launches. Although the February 2026 encounter did not involve dangerous maneuvers, its structural similarity—rapid scrambles in response to legitimate operations—aligns perfectly with this established behavior pattern.

This incident exemplifies the unstable equilibrium defining US-China military interactions in Northeast Asia. Even operations conducted legally under international norms can create escalation risks when carried out in areas where geopolitical distrust and conflicting narratives converge. The US and China finalized rules regarding aerial encounters in 2015, but, as the aforementioned dangerous intercept patterns indicate, compliance has been inconsistent. The absence of escalation in the February incident suggests that both militaries exhibited discipline, but a single instance of discipline does not eliminate the cumulative risks across repeated encounters.

At the same time, tensions are rising around Japan. On February 22, 11 Japanese fighter jets and 4 US B-52 strategic bombers conducted bilateral air exercises over the East China Sea and the Sea of Japan. Additionally, a Chinese submarine was spotted at one of Russia's major Pacific ports, raising alarms in Japan. Chinese Vice Foreign Minister Fu Ying stated on February 18 that Japan is attempting to "militarily intervene in the Taiwan issue under the pretext of collective self-defense," warning that this constitutes "an act of aggression against China."

These series of incidents indicate that the security environment in Northeast Asia is at a fundamental turning point. The expansion of USFK's role, the strengthening of the US-Japan alliance, heightened vigilance toward China's defense boundaries, and the intersection of economic interdependence and military competition—all contribute to making this region one of the most strategically important maritime areas in the world.

Unless there are structural confidence-building measures, the sustainability of such controlled confrontations will continue to test the resilience of regional stability. The Yellow Sea continues to function as both a physical battlefield and a psychological stage, where rapid scrambles and controlled confrontations reinforce the narrative of deterrence while maintaining the threshold for open confrontation. The future of Northeast Asia hinges on how this delicate balance is managed.