The Russian and Chinese aircraft entered and left the Korea Air Defence Identification Zone (Korea ADIZ) in the Sea of Japan, known in Korea as the East Sea, several times through the day, according to South Korea’s Joint Chiefs of Staff (JCS).

The aircraft, which included fighter jets and bombers from each side, did not violate South Korea’s airspace, the JCS added.

The South Korean military deployed air force fighters to “implement tactical measures” to brace for a potential contingency.

Unlike airspace, an ADIZ is usually an area where countries may unilaterally demand that foreign aircraft take special steps to identify themselves, with no international laws governing ADIZs.

Tuesday’s incursion was the first reported since new South Korean President Yoon Suk-yeol took office on May 10. On Sunday, Yoon wrapped up a summit with U.S. President Joe Biden where the two leaders pledged support for measures seen as countering China’s influence in the region, and criticised Russia’s war in Ukraine.

Moscow does not recognise the Korea ADIZ, while Beijing said the area is not territorial airspace and all countries should enjoy freedom of movement there.

In 2019, South Korean warplanes fired hundreds of warning shots toward Russian military aircraft when they entered South Korean airspace during a joint air patrol with China.

By Josh Smith and Hyonhee Shin.

(Reporting by Josh Smith and Hyonhee Shin; Editing by Raju Gopalakrishnan)