NATO Secretary-General Mark Rutte and Japan’s defense minister expressed “grave concerns” over a joint patrol by Chinese and Russian bombers that skirted Japanese airspace this week, Japan’s defense ministry said Wednesday.

The incident came amid rising tensions between Tokyo and Beijing after Prime Minister Sanae Takaichi made remarks about Taiwan that angered Chinese officials.

Concerns shared in call

The ministry said Rutte and Defense Minister Shinjiro Koizumi discussed the patrol in a 15-minute video conference late Wednesday and agreed to maintain close communication.

Koizumi also briefed Rutte on a separate confrontation in which Chinese aircraft locked radar onto Japanese planes near Taiwan, a move Tokyo described as dangerous and destabilizing.

Joint flight around Japan

According to Japan, two Russian Tu-95 nuclear-capable bombers flew from the Sea of Japan on Tuesday to meet two Chinese H-6 bombers over the East China Sea. The aircraft then conducted a joint flight around Japan, prompting Tokyo to scramble fighter jets.

South Korea said Russian and Chinese military aircraft also entered its air defense zone, leading Seoul to deploy warplanes in response.

Beijing confirmed Tuesday that it carried out drills with Russia under “annual cooperation plans,” while Moscow called the eight-hour operation a routine exercise. Russia said foreign fighters had shadowed the formation.

Takaichi last month suggested Japan would take military action if China attacked Taiwan. Beijing, which claims the island as its territory, denounced her comments and has not ruled out the use of force.