Seoul: South Korea said it had sent up fighter jets as a precaution after more than 10 Chinese and Russian military aircraft entered its air defence zone on Saturday.

The Joint Chiefs of Staff in Seoul said the Chinese and Russian aircraft had entered and then left the Korea Air Defence Identification Zone (KADIZ) over the East Sea and the South Sea.

"South Korea's military detected the Chinese and Russian aircraft before they entered the zone and deployed Air Force fighter jets to prepare for any contingency," it said in a statement, without giving more details.

The Chinese and Russian aircraft did not violate South Korean airspace, it said.

An air defence identification zone is not sovereign airspace but a buffer area where countries identify approaching aircraft for security purposes.

Military aircraft are generally expected to notify the relevant country before entering its air defence zone, although such notification is not legally required.

Beijing's defence ministry said in a statement that the Chinese and Russian air forces conducted a "strategic air patrol" over the Sea of Japan, the East China Sea and the western Pacific Ocean, "demonstrating their determination and capability to jointly uphold regional peace and stability".

The brief statement did not specifically mention South Korea or its air defence zone.

Russia did not immediately comment on the incident.

South Korea and Japan reacted furiously when nine Chinese and Russian military aircraft entered the KADIZ in December 2025, the previous such incident.

South Korea's defence ministry lodged protests with Beijing and Moscow over that incident, while Japan expressed its "serious concern" over national security.

China and Russia said the flights were part of a joint patrol over the East Sea and the western Pacific.