New Delhi, Dec. 12 -- 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.

Early Friday, Japanese Defense Minister Shinjiro Koizumi and his U.S counterpart, Pete Hegseth, held telephone t...