The South Korean military said it scrambled fighter jets on Wednesday after six Russian and two Chinese warplanes unexpectedly entered its air defence zone.
According to Seoul's Joint Chiefs of Staff (JCS), Chinese H-6 bombers repeatedly entered and exited the Korea Air Defence Identification Zone (KADIZ) near South Korea's southern and northeast coasts early Wednesday.
They returned to the zone hours later from the East Sea, also known as the Sea of Japan, accompanied by Russian warplanes including two Su-35 fighter jets and four TU-95 bombers, according to the report.
According to Seoul, the warplanes eventually left the zone and did not violate South Korean airspace.
An ADIZ is a larger area than a country's airspace in which it attempts to control aircraft for security reasons, but it is not defined in any international treaty.
“Our military deployed air force fighter jets even before Chinese and Russian aircraft entered the KADIZ to take tactical measures in the event of a contingency,” said the JCS in a statement.
According to unidentified “observers,” Beijing and Moscow appeared to have “engaged in a combined air exercise.”
The incident occurs as Washington presses China, Pyongyang’s most important ally, to use its influence to help rein in North Korea, which has launched a record number of missiles this year.
Chinese President Xi Jinping recently told North Korean leader Kim Jong Un that he would collaborate with him for “world peace.”
Pyongyang earlier this month conducted one of its most potent missile tests, declaring that it would respond to perceived US nuclear threats with nuclear weapons of its own.
The US has accused Beijing and Moscow of shielding Pyongyang from further sanctions.
In response to the North's previous missile launches, the two countries vetoed a US-led effort to tighten sanctions on North Korea in May.