On May 3rd a China Coast Guard helicopter launched from a patrol vessel entered Japanese airspace over the disputed Senkaku Islands, prompting a rapid response from the Japan Air Self-Defense Force (JASDF). This incident marks an escalation in China’s ongoing gray zone efforts against Japan, as it continues to assert its claims over the uninhabited Japanese controlled islets in the East China Sea. The event has triggered diplomatic protests from both governments and reignited debate in Tokyo over the adequacy of the JASDF’s current defense posture.

According to the Japanese Ministry of Defense, four China Coast Guard vessels entered Japanese territorial waters around the Senkaku Islands at approximately 12:20 on May 3rd. One vessel launched a helicopter which remained in Japanese airspace for about 15 minutes, from 12:21 to 12:36. Japanese Coast Guard patrols visually confirmed the incursion and issued repeated warnings to the Chinese ships, all of which were equipped with autocannons. In response, two JASDF F-15 fighter jets scrambled from the Naha Air Base in Okinawa, though they did not fire weapons or deploy flares.

Satellite imagery and automatic information system (AIS) data confirm that Chinese government vessels have maintained a near-constant presence in the area for 166 consecutive days, with this being the 11th confirmed incursion into Japanese territorial waters in 2025 alone. The helicopter’s flight path was observed by the Japan Coast Guard’s 11th Regional Headquarters in Naha.

The May 3 intrusion is the fourth confirmed violation of Japanese airspace by a Chinese aircraft since World War II, and the third such incident specifically around the Senkaku Islands. The timing of the aerial incursion coincided with the presence of a Japanese civilian aircraft in the vicinity, which Chinese authorities later claimed had illegally entered their airspace, prompting the helicopter’s deployment as a retaliatory measure. Both governments lodged formal protests: Japan’s Vice Minister for Foreign Affairs, Takehiro Funakoshi, summoned China’s ambassador in Tokyo, while China’s foreign ministry summoned a Japanese envoy in Beijing.

The Senkaku Islands, called Diaoyu by China, are administered by Japan but also claimed by both China and Taiwan. The sovereignty dispute has intensified since the late 1960s, when potential undersea resources were identified in the region. China’s pattern of incremental incursions, sometimes referred to as “salami slicing”, aims to establish de facto control without triggering open conflict.

This incident highlights the evolving nature of “gray zone” maritime competition. China’s use of coast guard vessels and helicopters--rather than navy warships or fighter jets--enables persistent pressure while avoiding the overt escalation associated with military force. The deployment of a helicopter from a coast guard ship, rather than a military aircraft blurs the line between law enforcement and military operations, complicating Japan’s response options.

Japan’s reliance on fast, high-performance fighter jets like the F-15J for airspace defense is effective against conventional threats but less suited to intercepting slower-moving helicopters or drones. Should these exercises become more commonplace, such responses by the Japanese risk wearing down Japan’s limited fighter fleet, especially as China’s air and maritime assets far outnumber those of the JASDF. Recent months have also seen an uptick in Chinese drone activity near Okinawa, further straining Japanese air defense resources.

The May 3 airspace violation underscores the persistent and evolving nature of China’s gray zone tactics in the East China Sea. While both governments have exchanged diplomatic protests, the operational reality is that China continues to test--and gradually encroach upon--the boundaries of Japanese administrative control around the Senkaku Islands. The incident exposes the limitations of Japan’s current air defense posture and highlights the need for adaptive, multi-agency responses that can address the full spectrum of gray zone activity.

Note: For an in-depth discussion of China's sophisticated maritime gray zone tactics see this recent podcast episode, Why Should We Care About China's Gray Zone Warfare with RAND Corporation's Todd Helmus, hosted by SeaLight Director Ray Powell and Jim Carouso (also available on audio podcast services):