Japan, China Continue Trading Barbs Over Radar Incident; Tokyo Rejects Claim That Advance Notice of Training Was Provided

The Yomiuri Shimbun

7:00 JST, December 22, 2025

Half a month after Chinese fighter aircraft directed radar at Air Self-Defense Force jets, Japan and China continue trading barbs over whether China gave advance notice of its training operations and over the danger of directing radar.

According to the Japanese Defense Ministry, fighter aircraft that took off from the Chinese Navy’s Liaoning aircraft carrier twice directed radar at ASDF fighter jets that were conducting surveillance over international waters in the western Pacific southeast of Okinawa Island on Dec. 6.

However, China insists that the SDF jets intruded into training zones that China had set up. It also claims that it notified Japan in advance of aircraft training on the same day, and has released audio that it says is from a radio exchange between the Chinese military and the SDF before the training began.

Japan views it as problematic that China failed to issue in advance a Notice to Airmen (NOTAM), which informs others where an exercise is taking place in a maritime zone or airspace, and a navigation warning to vessels. The SDF issues such notices prior to training, and it is common practice to call on civil vessels and aircraft to be vigilant.

International law does not require advance notice of training. However, Kazuhisa Shimada, a former vice minister of defense, believes it was necessary in the case in question.

“The training zones in this case were close to Japanese territory, and what China claims was a ‘notice’ is not regarded as advance notice, which was needed,” Shimada said. “China should have issued a NOTAM or another form of notice.

“Even if advance notice had been given, that would not give China a reason to direct radar [at SDF jets],” he said.

Defense Minister Shinjiro Koizumi revealed the incident in the early hours of Dec. 7, shortly after it took place. Koizumi told a news conference in the morning of Dec. 9 that China had not provided advance notice of its military training. In the afternoon on the same day, China released audio that it claimed was from a radio exchange between the Chinese military and the SDF.

It remains unknown whether Koizumi was informed of the radio exchange, but the timing of the announcement greatly angered a senior SDF official. “China is attempting to give the impression that Japan is wrong and set up a straw man,” the official said.

The Japanese government thinks the essential problem in the current dispute is the Chinese aircraft’s act of intermittently directing radar for about 30 minutes.

China argues that using search radar during flight training is common among different countries. It is highly dangerous if radar is directed for the purpose of fire control, an act of target acquisition in preparation for shooting, but China has not made it clear whether radar was directed for that purpose.

In response, Japan countered that fighter jets’ radar can be used for the purpose of fire control. It went on to say that directing radar for an extended time is a dangerous act that could result in a military clash.

In 2013, another time when Japan-China relations were strained, a Chinese Navy frigate pointed fire-control radar at a Maritime Self-Defense destroyer.

In the current dispute, China is believed to be using its old ploys of overpowering its adversary and making provocations. Similar incidents might happen in the future.

“It will be crucial to establish rules and relationships to prevent collisions during exercises on the high seas,” said Prof. Akira Mayama of Osaka Gakuin University, an expert on international law.