US nuclear-capable bombers joined Japanese fighter planes for a flight over the Sea of Japan, Tokyo said Thursday.

This comes a day after Chinese and Russian forces completed coordinated drills encircling Japan and South Korea.

"We confirmed the strong resolve of Japan and the United States not to allow any unilateral change of the status quo by force, as well as the readiness of the Self-Defense Forces and the US military," Japan's Defense Ministry said in a statement.

Two US B-52 bombers joined three Japanese F-35 stealth fighters and three F-15 jets in the operation on Wednesday.

Chinese-Russian bomber flights patrol region

It was the first such display since China began military exercises in the region last week.

Japan scrambled jets late Tuesday to monitor Chinese and Russian fighters and bombers conducting joint patrols around the country.

"We consider it a grave concern from the standpoint of Japan's security," Japan's Chief of Staff, Joint Staff General Hiroaki Uchikura said.

Beijing and Moscow described their drills as a routine exercise.

"The Japanese side has no need to make a fuss about nothing or to take this personally," Chinese Foreign Ministry spokesperson Guo Jiakun said.

Over the weekend, when Chinese fighter planes locked radars on Japanese aircraft in the most serious run-in between the East Asian militaries in years.

Illuminating an aircraft with radar signals a potential attack, often forcing targeted planes to take evasive action.

The Chinese planes were part of a carrier strike group sailing close to Japan.

"China's actions are not conducive to regional peace and stability," a US State Department spokesperson told AFP on Wednesday.

Beijing and Moscow described their drills as a routine exercise.

South Korea, Taiwan react to Chinese military activity

South Korea said it scrambled fighter jets after Chinese and Russian aircraft entered its air defense identification zone on Tuesday.

Meanwhile, Taiwan reported a surge in Chinese military activity for the second day in a row. Its defense ministry said 27 aircraft, including nuclear-capable H-6K bombers, carried out joint patrols with warships around the island.

On Wednesday, Chinese J-16 fighters and H-6 bombers also conducted long-range drills in the Western Pacific after passing south of Taiwan.

Relations between Japan and China have worsened after Japan's Prime Minister Sanae Takaichi said in early November its military could get involved if China were to take action against Taiwan, the self-governing island that Beijing claims as its own.

Edited by Karl Sexton