South Korea and Japan scramble fighter jets as Chinese Russian bombers run joint Pacific patrol.

South Korea and Japan launched F-15 series fighters on 10 December 2025 after Chinese and Russian bombers and support aircraft flew joint patrol routes through their air defense identification zones over the Sea of Japan, the East China Sea, and the western Pacific. The coordinated sortie, part of an expanding pattern of Sino-Russian strategic air patrols, is testing allied air policing capacity and sharpening debate over deterrence and escalation in Northeast Asia.

South Korea and Japan scrambled fighter jets on Wednesday after Russian Tu-95 and Chinese H-6 bombers, escorted by Chinese J-16 fighters and supported by a Russian A-50 airborne early warning aircraft, conducted a long-range joint patrol along their airspace approaches, according to the two governments. Seoul reported that seven Russian and two Chinese aircraft entered and exited the Korea Air Defense Identification Zone over roughly one hour, without breaching territorial airspace, while Tokyo said its F-15J fighters shadowed the bomber package as it moved from the Sea of Japan toward the East China Sea and out into the western Pacific.
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South Korea and Japan scramble F-15 fighters as Chinese and Russian bombers fly a joint patrol through their ADIZs, raising pressure on allied air defenses. (Picture source: South Korean and Japanese MoD) 

The Korea Air Defense Identification Zone (KADIZ) functions as an early warning belt used to identify and track aircraft approaching the peninsula beyond national airspace. It is not sovereign airspace under international law, but regional practice expects foreign military aircraft to identify themselves when they enter such zones. In this case, the Sino-Russian package combines long-range strike platforms and enablers. The Tu-95, powered by four Kuznetsov NK-12 turboprop engines, can fly more than 10,000 km without refuelling and carry long-range cruise missiles under its wings. The Chinese H-6, derived from the Soviet-era Tu-16 but modernised in successive variants, can be fitted to launch anti-ship or land-attack missiles guided by an onboard navigation and targeting radar. J-16 multirole fighters, equipped with active electronically scanned array radars and beyond-visual-range air-to-air missiles, provide close protection to the bomber formation. The Russian A-50, based on the Il-76 airframe and fitted with a rotating Vega Shmel radar, offers airborne early warning and control over several hundred kilometres, fusing tracks from multiple directions.

South Korea’s response relies on the standing alert posture of its F-15K squadrons. The F-15K, a twin-engine multirole fighter, operates with a modern active electronically scanned array radar able to detect and track large targets at ranges in excess of 150 km, even in complex clutter over sea. Its F110 afterburning turbofan engines give it the thrust needed to reach interception points quickly from inland bases. Airborne data are complemented by ground-based long-range surveillance radars feeding into the national command and control (C2) network, which correlates primary radar returns, identification friend or foe signals, and track histories. According to the Joint Chiefs of Staff, the Chinese and Russian aircraft are detected before they reach the KADIZ boundary, are monitored throughout their time in the zone, and never violate South Korea’s territorial airspace. Fighter sorties are launched as a precaution and remain ready to adjust profiles should any aircraft alter course toward national territory, while Seoul also files a diplomatic protest with Chinese and Russian representatives.

Tokyo adopts a similarly structured posture as the joint bomber patrol moves along Japanese approaches. Japan scrambles F-15J fighters from the Japan Air Self-Defense Force (JASDF) Southwestern Air Defense Command to shadow the Tu-95 and H-6 bombers as they move from the Sea of Japan toward the East China Sea and then out into the Pacific off Shikoku. The F-15J, fitted with upgraded radar and AAM-4B air-to-air missiles featuring active radar guidance, is intended to maintain engagement options against both bombers and their J-16 escorts at stand-off distances. Japanese reporting indicates that additional J-16 fighters join the bombers between Okinawa and Miyako Island on both the outbound and inbound legs. At the same time, Japan continues to monitor the operations of the Chinese aircraft carrier Liaoning and its escorts east of Kita Daito Island, where J-15 carrier-borne fighters and helicopters have conducted roughly 140 take-offs and landings over three days, including radar locks on Japanese F-15s during recent encounters.

The technical and operational pattern of these activities shows how China and Russia exploit the depth of KADIZ and Air Defense Identification Zone (ADIZ) arrangements around South Korea and Japan. By sending mixed formations of bombers, fighters, and an A-50 command post through international airspace adjacent to national airspace, they test detection thresholds, reaction times, and the sustainability of interception routines. For the South Korean Air Force, each patrol requires timely coordination between ground controllers and F-15K crews, careful management of fuel and weapons loads, and constant readiness to transition from monitoring to active engagement if flight profiles change. For Japan, whose defensive lines stretch across the Nansei island chain, repeated scrambles over long distances impose cumulative pressure on fighter availability and maintenance cycles, while also requiring continuous tracking of the Liaoning carrier group and accompanying People’s Liberation Army Navy (PLAN) surface ships and frigates moving through key straits.

At the tactical level, these flights are designed to remain just below escalation thresholds while still conveying intent. Russian and Chinese aircraft stay in international airspace and limit their activity to KADIZ and ADIZ corridors, but the repetition of these routes once or twice a year since 2019, including a previous large-scale flight through the South Korean zone in November 2024, indicates a deliberate pattern rather than isolated events. South Korea responds by lodging diplomatic protests in parallel with its air measures, indicating that it views the incursions into the identification zone as a challenge to regional stability even without a formal breach of airspace. Japan, for its part, frames the patrols as part of a wider increase in military activity around its territory, pointing to recent incidents of Chinese J-15 fighters using fire-control radar against Japanese aircraft and to the sustained presence of the Liaoning carrier strike group near Okinawa.

The broader geopolitical context gives these patrols a clear strategic meaning. Sino-Russian cooperation in the air domain has expanded since 2019 in step with their political alignment, reinforced by the Russian campaign in Ukraine and by China’s more assertive posture around Taiwan. For Japan, which plans to deploy additional electronic warfare and air defence assets on forward islands such as Yonaguni, the latest flights underline the need to adapt a traditionally defensive force structure to a more demanding environment. For South Korea, the intersection of regular KADIZ intrusions, North Korean missile and drone activity, and dense maritime traffic increases the challenge of maintaining credible air vigilance across multiple axes. The United States remains a central partner for both Seoul and Tokyo through combined exercises and strategic bomber deployments in the region. As joint Chinese-Russian patrols continue and carrier operations increase in contested waters, airspace management in the western Pacific is likely to become more complex, and air defence cooperation between regional allies will remain a core element of the security architecture in Northeast Asia.