Beijing's actions are "not conducive to regional peace", Japan's defense minister and US counterpart Pete Hegseth agreed during a call after Chinese aircraft locked radar on Japanese jets near Taiwan, Tokyo said Friday.
The December 6 radar incident came after comments by Prime Minister Sanae Takaichi on Taiwan that infuriated China, AFP reported.
It was followed this week by Chinese-Russian air patrols around Japan.
Hegseth and Shinjiro Koizumi "exchanged candid views on the increasingly severe security situation in the Indo-Pacific region, including the radar incident", the Japanese defense ministry said after the call.
They "expressed serious concern over any actions to increase regional tensions, as China's actions are not conducive to regional peace and stability", the statement added.
Koizumi said on X he told Hegseth that China was "disseminating information that is completely contrary to the facts" about the radar incident.
"However, Japan has made clear that it does not seek escalation and that we are responding calmly while making necessary rebuttals, and we are keeping the door open for dialogue," Koizumi added.
Hegseth's office said they had "discussed... China's military activities" among other issues including "Japan's efforts to increase its defense spending and strengthen its capabilities".
'Tactical exercises'
Takaichi had indicated on November 7 that Japan would intervene with military force in any Chinese attack on Taiwan, which Beijing claims as its own and has not ruled out seizing by force.
Media reports on Friday reinforced suggestions that her comments in a parliamentary debate were unplanned and that she deviated from prepared remarks.
Last week, J-15 jets from China's Liaoning aircraft carrier twice locked radar on Japanese aircraft that had scrambled in international waters near Okinawa, according to Japan.
Fighter jets use their radar for fire control to identify targets as well as for search and rescue operations.
But China's foreign ministry on Wednesday accused Japan of sending the jets "to intrude into the Chinese training area without authorization, conduct close-range reconnaissance and harassment, create tense situations, and... maliciously hype up the situation".
On Tuesday two Russian Tu-95 nuclear-capable bombers flew from the Sea of Japan to rendezvous with two Chinese H-6 bombers in the East China Sea, then conducted a joint flight around the country, Japan said.
Japan said that it scrambled fighter jets in response.
A day later, Japan and the United States air forces conducted their own joint air drills, Tokyo said.
The "tactical exercises" over the Sea of Japan involved two US B52 bombers, three Japanese F-35 fighter jets and three Japanese F-15s, Tokyo said.
South Korea said Tuesday that Russian and Chinese warplanes also entered its air defense zone, with Seoul also deploying fighter jets that same day.
Beijing confirmed on Tuesday that it had organized drills with Russia's military according to "annual cooperation plans".
Moscow also described it as a routine exercise, saying it lasted eight hours and that some foreign fighter jets followed the Russian and Chinese aircraft.
