Photo/Illutration Defense Minister Shinjiro Koizumi, right, and U.S. Secretary of War Pete Hegseth at the Defense Ministry in Tokyo on Oct. 29 (Asahi Shimbun file photo)

Japanese Defense Minister Shinjiro Koizumi and his U.S counterpart, Pete Hegseth, held telephone talks on “increasingly severe security situation in the Indo-Pacific region, including the radar incident,” the Japanese defense ministry said on Friday in a statement.

It said the ministers expressed serious concern over any actions to increase regional tensions, as “China's actions are not conducive to regional peace and stability.” Koizumi reiterated that Japan will firmly and steadily continue surveillance and monitoring activities in the airspace and waters surrounding the country.

U.S. strategic bombers joined a fleet of Japanese fighter jets in a joint military exercise meant to demonstrate their military cooperation around Japan's airspace, defense officials said Thursday, as tensions with China escalate.

The exercise showcasing joint Japanese-U.S. air power came a day after Chinese and Russian bombers flew together around western Japan, prompting Tokyo to scramble fighter jets, though there was no airspace violation. It also follows China's military aircraft locking radar on Japanese jets Saturday, another incident that has caused Tokyo-Beijing relations to further deteriorate.