Overview
On December 6, 2025, two Chinese J-15 carrier-based fighter jets from the aircraft carrier Liaoning intermittently illuminated their fire-control radar on Japanese Air Self-Defense Force (ASDF) F-15 fighters over international waters southeast of Okinawa, in two encounters lasting roughly three minutes and about thirty minutes respectively. Japan’s defense minister Shinjiro Koizumi denounced the radar lock-ons—which militaries treat as the step immediately before weapons launch—as “dangerous” and “extremely regrettable,” and Tokyo lodged a formal protest with Beijing. Analysts noted this was the first publicly acknowledged fire-control radar lock between Chinese and Japanese military aircraft, echoing a 2013 episode when a Chinese frigate locked weapons radar on a Japanese destroyer near the disputed Senkaku/Diaoyu Islands.
The radar incidents capped a month of intensifying friction triggered by new Prime Minister Sanae Takaichi’s November 7 remarks that a Chinese use of force against Taiwan could create a “survival‑threatening situation” justifying Japanese military involvement under collective self‑defense laws. China responded with diplomatic protests, travel and study warnings for its citizens, increased coast guard and drone activity around the Senkaku Islands and Japan’s southwestern islands, and a fresh coast guard standoff with Japan on December 2. Against a backdrop of hundreds of annual Japanese scrambles against Chinese aircraft and expanding Chinese carrier drills through the Miyako Strait, the Okinawa radar lock-ons have raised concerns in Tokyo, Washington, Canberra, and Taipei that a miscalculation in this crowded air–sea corridor could rapidly drag multiple powers into a crisis over Taiwan and the East China Sea.
Key Indicators
People Involved
Organizations Involved
Japan’s Ministry of Defense (MOD) oversees the Self‑Defense Forces and is responsible for defense policy, operations, and procurement.
The ASDF is Japan’s air arm, operating fighter, surveillance, and transport aircraft to defend Japanese airspace and monitor surrounding regions.
The PLA is China’s armed forces, comprising ground, naval, air, rocket, and strategic support forces, and is central to Beijing’s efforts to project power in the Western Pacific.
The China Coast Guard (CCG) is Beijing’s main maritime law-enforcement force, heavily armed and frequently deployed to assert China’s claims in contested waters.
Australia’s Department of Defence manages the Australian Defence Force (ADF) and defence policy, including the AUKUS partnership and regional security cooperation.
Timeline
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Japan and Australia agree to deepen security cooperation after radar incident
Alliance CoordinationAt a meeting in Tokyo, Japanese Defence Minister Shinjiro Koizumi and Australian Defence Minister Richard Marles describe China’s behavior in the East and South China seas as increasingly coercive and agree to strengthen security ties. Koizumi references the radar lock incident; Marles calls the situation ‘very worrying.’
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Japan protests radar locks as ‘dangerous’ and ‘regrettable’
Diplomatic ProtestDefense Minister Shinjiro Koizumi briefs reporters in the early hours of December 7, calling the radar locks “a dangerous act that exceeded the scope necessary for safe aircraft operations” and “extremely regrettable.” Japan summons Chinese officials and lodges a strong protest, demanding measures to prevent recurrence.
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Carrier Liaoning passes between Okinawa and Miyako during drills
Military MovementChina’s aircraft carrier Liaoning, escorted by three destroyers, transits between Okinawa’s main island and Miyako Island into the western Pacific while conducting intensive takeoff and landing drills for J-15s and helicopters. The radar lock incidents occur as ASDF F-15s shadow these operations.
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Second, longer radar lock-on incident over Miyako–Okinawa corridor
Military EncounterJapan reports that another J-15 from Liaoning intermittently illuminates its fire-control radar on a different ASDF F-15 for roughly 30 minutes in the evening, again over international waters near Okinawa. No Japanese airspace is violated and no damage occurs, but Tokyo regards the sustained radar targeting as a grave threat.
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First reported radar lock: Chinese J-15 targets ASDF F-15 southeast of Okinawa
Military EncounterAccording to Japan’s Defense Ministry, a Chinese J-15 fighter launched from the carrier Liaoning intermittently directs its fire-control radar at an ASDF F-15 over international waters southeast of Okinawa for about three minutes. The Japanese jet had been scrambled in response to potential airspace intrusion.
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Chinese and Japanese coast guards face off near Senkaku/Diaoyu
Maritime ConfrontationChinese and Japanese coastguard vessels engage in a standoff around the disputed Senkaku/Diaoyu Islands. China says its ships took ‘necessary control measures’ to expel a Japanese fishing boat from Chinese territorial waters; Japan says it intercepted and drove off Chinese coast guard ships that approached a Japanese fishing vessel.
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Chinese foreign ministry attacks Japan’s talk of collective self-defense over Taiwan
Public StatementForeign ministry spokesperson Mao Ning says Japan’s suggestion it could exercise collective self-defense in a Taiwan contingency is unacceptable, citing World War II–era restrictions that Japan should not ‘re-arm,’ and warns Tokyo to retract ‘wrongful remarks’ about Taiwan.
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China issues travel warning and ramps up activity near Senkaku after Takaichi remarks
Diplomatic EscalationChina’s embassy in Tokyo advises Chinese citizens to avoid travel to Japan, citing an ‘unstable’ atmosphere caused by Takaichi’s Taiwan comments. Around the same time, China sends coast guard ships through the Senkaku/Diaoyu waters and flies military drones close to Japan’s southwestern islands and near Taiwan, stepping up gray‑zone pressure on Tokyo.
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Takaichi states a Chinese attack on Taiwan could trigger Japanese military response
Public StatementIn a Diet session, Prime Minister Takaichi says that a Chinese attempt to seize Taiwan using warships and force could constitute a ‘survival‑threatening situation’ for Japan, potentially justifying the use of collective self-defense and SDF deployment. The remarks break with prior Japanese ambiguity and provoke a strong reaction from Beijing.
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Sanae Takaichi becomes LDP leader, poised to be first female PM
Political ShiftConservative lawmaker Sanae Takaichi wins the Liberal Democratic Party leadership contest, defeating Shinjiro Koizumi in a runoff and positioning herself to become Japan’s first female prime minister. Her hawkish views on China and Taiwan signal a potentially firmer Japanese security posture.
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Japan reports 704 scrambles in FY2024, most against Chinese aircraft
Data PointJapan’s Ministry of Defense announces that ASDF jets scrambled 704 times in fiscal 2024, up from 669 in FY2023; 464 scrambles (about 66%) responded to Chinese aircraft, underscoring the sustained tempo of Chinese air activity around Japan, including near Okinawa and Miyakojima.
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Chinese frigate locks weapons radar on Japanese destroyer near Senkaku/Diaoyu
Military EncounterJapan reveals that a Chinese Jiangwei II–class frigate locked its fire-control radar on a Maritime Self-Defense Force destroyer on January 30, 2013, and on a helicopter earlier that month, near the disputed Senkaku/Diaoyu Islands. Tokyo calls it a “very dangerous act” and lodges a formal protest; Beijing denies using fire-control radar and accuses Japan of hyping the incident.
Scenarios
Managed De-escalation and New Air–Sea Safety Protocols
Discussed by: Regional security analysts in Japan, Australia, and the US; coverage by Reuters, AP, and think-tank commentary emphasizing risk-management mechanisms
In this scenario, both Tokyo and Beijing treat the radar lock incidents as a warning shot rather than a new normal. Japan continues to protest vigorously but avoids tactical escalation, while China quietly instructs carrier aviation units to avoid sustained fire-control radar illumination against Japanese jets unless necessary. Behind the scenes, Japan, the US, and other regional navies push to expand the 2014 Code for Unplanned Encounters at Sea (CUES) into air encounters, and to reinforce existing hotlines between defense ministries to manage incidents. The episode becomes a case study in near-crisis management similar to the 2013 naval radar lock, which was not repeated in the following years.
Normalization of Dangerous Encounters in the Okinawa–Taiwan Corridor
Discussed by: Foreign Affairs and other strategic publications that warn of ‘crowded waters and airspace’ around the Senkaku and Taiwan area; Japanese defense white papers tracking rising scrambles
Here, the radar locks are not a one-off but an early marker of a new pattern. PLA pilots grow more willing to use fire-control radar, aggressive interceptions, and close passes in the Miyako–Okinawa and Senkaku zones, mirroring behavior already seen toward US and Australian patrol aircraft. Japanese scrambles remain high or increase, and both sides’ pilots and ship captains become habituated to brinkmanship. No single incident crosses a red line, but the cumulative effect is a higher probability of an accident or miscalculation. Domestic political pressure in Japan leads to further defense build‑up in Okinawa and the outer islands, reinforcing a spiral of action and reaction.
Trigger Incident Leading to a Limited Armed Clash
Discussed by: Worst-case analyses by some defense commentators drawing on past close calls, including the 2001 Hainan EP-3 collision and 2013 radar lock near the Senkaku/Diaoyu Islands
In this scenario, a future encounter goes wrong: a radar lock is misread as preparation for attack, or an aggressive intercept results in a mid-air collision. A Japanese or Chinese aircraft is lost, or weapons are fired in self‑defense. Nationalist outrage and alliance dynamics make de-escalation difficult, leading to a brief but intense exchange of fire around the Senkaku Islands or the Okinawa approaches. The US and possibly Australia are drawn in at least diplomatically, and crisis management resembles the 2001 Hainan incident but with more capable forces and a higher risk of escalation. While leaders on both sides likely want to avoid full-scale war, they may feel compelled to demonstrate resolve before stepping back.
Prelude to a Taiwan Blockade or Invasion Involving Japan
Discussed by: Some Taiwan-focused analysts and hawkish commentators linking Liaoning’s activities and radar locks to Xi’s reported 2027 readiness goal for taking Taiwan
Under this scenario, the December 2025 radar incidents are part of a deliberate Chinese campaign to normalize high‑risk operations along the routes Japan and the US would need to use in a Taiwan contingency. Carrier drills, coast guard confrontations, and aggressive air intercepts condition regional actors to PLA presence and test their responses. If Beijing moves to blockade or attack Taiwan, it is prepared to simultaneously pressure Japan around Okinawa and the Senkaku to deter Japanese and US intervention. Tokyo, having already signaled its willingness to consider collective self-defense over Taiwan, feels compelled to respond militarily, transforming a localized radar dispute into a wider war scenario.
Political Backlash and Recalibration of Japan’s Taiwan Signaling
Discussed by: Domestic Japanese commentators and opposition politicians concerned that Takaichi’s explicit Taiwan remarks may have provoked avoidable Chinese escalation
In this outcome, political criticism inside Japan focuses less on Chinese behavior—viewed as predictably assertive—and more on whether the prime minister’s explicit Taiwan comments needlessly raised the risk of confrontation. If business lobbies feel economic pain from Chinese travel and study curbs and insurers and airlines grow nervous about the Okinawa region, pressure may build for more carefully scripted official language on Taiwan, even as defense policies continue to tighten. The government might reaffirm its right to collective self-defense in broad terms but choose not to spell out specific Taiwan scenarios in public, attempting to reduce friction while still deterring Beijing.
Historical Context
2013 China–Japan Naval Fire-Control Radar Incident
January–February 2013What Happened
In January 2013, a Chinese frigate reportedly locked its fire-control radar—used for targeting weapons—on a Japanese Maritime Self-Defense Force destroyer near the disputed Senkaku/Diaoyu Islands, and earlier on a Japanese helicopter. Japan publicly revealed the incidents in early February, calling them ‘very dangerous acts’ and lodging a formal protest. China denied using fire-control radar and accused Japan of fabricating the allegations and hyping a ‘China threat’, but the episode marked the most acute military standoff in the East China Sea dispute up to that point.
Outcome
Short term: Despite mutual recriminations, no shots were fired and both sides avoided further radar incidents in the immediate aftermath, though coast guard and air encounters around the islands continued at a high tempo.
Long term: The incident became a reference point for how close China and Japan had come to accidental conflict and underscored the need for hotlines and risk-reduction measures, but it did not prevent a gradual normalization of frequent, lower-level confrontations around the Senkaku/Diaoyu area.
Why It's Relevant
The 2013 episode shows how fire-control radar use is perceived in Tokyo as one step short of firing and why similar radar locks in 2025 are treated as qualitatively more escalatory than routine shadowing. It also demonstrates that both governments previously pulled back from repeating such behavior for years, suggesting that normalization of radar locks is not inevitable but depends on political choices.
2018 Japan–South Korea Radar Lock-On Dispute
December 2018–June 2024What Happened
On December 20, 2018, Japan accused a South Korean destroyer of directing its STIR-180 fire-control radar at a Japanese P-1 maritime patrol aircraft during a rescue operation in the Sea of Japan. Tokyo said the radar irradiation was continuous and dangerous, violating the Code for Unplanned Encounters at Sea (CUES), while Seoul insisted it had used a different search radar and accused the Japanese aircraft of unsafe low-altitude flying. The dispute spiraled into a bitter diplomatic row, with Japan releasing cockpit video and both sides hardening positions. Only in June 2024 did the two governments agree on steps to prevent a recurrence, effectively shelving the disagreement without fully resolving it.
Outcome
Short term: Bilateral defense ties between two US allies deteriorated, with Japan curbing intelligence-sharing and joint exercises with South Korea for several years, even though no weapons were fired.
Long term: By 2024, shared concerns over North Korea and China pushed Tokyo and Seoul to repair ties and establish new procedures to avoid repeat incidents, illustrating that radar disputes can be politically toxic yet ultimately manageable with political will and alliance pressure.
Why It's Relevant
This case underscores how even non-fatal radar lock incidents can poison security cooperation and dominate diplomatic agendas for years. It demonstrates the importance of technical fact‑finding, communication protocols, and political leadership in resolving disputes over what sensors were used and why—lessons that will be crucial if Japan and China wish to prevent the Okinawa incident from locking their relationship into a prolonged crisis.
2001 Hainan Island EP-3 Collision
April 1–12, 2001What Happened
On April 1, 2001, a US Navy EP‑3E signals intelligence aircraft flying near China’s Hainan Island collided with a Chinese J‑8II interceptor that had been conducting close passes. The Chinese fighter broke apart and its pilot was presumed dead; the damaged EP‑3 made an emergency landing on Hainan, and its 24 crew members were detained by China. The incident triggered a tense ten‑day diplomatic standoff between Washington and Beijing over responsibility for the collision and the fate of the crew and the aircraft.
Outcome
Short term: China detained the US crew and demanded an apology; the US expressed “regret” without fully accepting blame. The crew was eventually released, and the aircraft was later disassembled and returned.
Long term: The episode highlighted the risks of aggressive intercept tactics and led to renewed efforts to improve air and maritime safety protocols, but it did not halt US surveillance flights or Chinese intercepts, leaving a persistent risk of future close calls.
Why It's Relevant
The Hainan collision shows how quickly routine intercepts can produce a fatal accident and international crisis, even without fire-control radar use. It is a cautionary precedent for the crowded airspace around Okinawa and Taiwan, where sustained radar lock-ons and close escorts like those reported in December 2025 could produce a similar or worse outcome if pilots misjudge distance or intent.