South Korea said it scrambled fighter jets to respond to a group of Russian and Chinese warplanes that entered its air buffer zone unannounced.

South Korea’s Joint Chiefs of Staff said it detected seven Russian and two Chinese military aircraft in the country’s air defence identification zone off its eastern coast.

Anticipating the moves, South Korea had already sent fighter jets and other aircraft to the area to prevent accidental clashes, but the Russian and Chinese planes left without breaching South Korea’s territorial airspace, the Joint Chiefs of Staff said.

China later told South Korea through a military communication channel that the flights were part of its routine military exercises with Russia.

“(We) assess the current situation as a joint exercise between China and Russia and additional analysis is needed,” the Joint Chiefs of Staff said in a statement.

The Russian defence ministry said in a statement on Friday that the Russian military was conducting joint aerial patrols with China.

On Friday, “an air group consisting of two Tu-95MS strategic bombers of the Russian Aerospace Forces and two Hun-6K strategic bombers of the Air Force of the People’s Liberation Army of China carried out aerial patrols over the waters of the Sea of Japan and the East China Sea”, it said.

The ministry said the joint patrol was carried to further develop Russian-Chinese relations, improve coordination between the two armed forces and for “strengthening global strategic stability”.

Air defence identification zones usually expand beyond the country’s territory to allow more time to respond to potentially hostile aircraft. Military planes entering another country’s air defence identification zone are required to notify it in advance.

Chinese and Russian warplanes have often entered South Korea’s air defence identification zones in recent years as they increasingly flex their muscle amid an intensifying competition with the United States.

In 2019, South Korea said its fighter jets fired hundreds of warning shots toward a Russian military plane that it said twice violated its national airspace off its eastern coast.

Russia then denied that its aircraft entered South Korea’s territory.