South Korea's Joint Chiefs of Staff said that Russian and Chinese aircraft entered the Korea Air Defense Identification Zone (KADIZ) at around 10 a.m. local time (0100 UTC/GMT) on Tuesday. 

Seoul said it deployed "fighter jets to take tactical measures in preparation for any contingencies" in response. 

But the military said the planes did not violate South Korea's air space, only entering the wider KADIZ area it monitors for security reasons. 

They flew in an out of the zone in operations lasting an hour before leaving the area, South Korean news agency Yonhap reported the military as saying. 

China reports joint exercises with Russia

China's Defense Ministry later said that it had organized drills with Russia's military as part of "annual cooperation plans." 

The "10th joint strategic air patrol" took place above the East China Sea and western Pacific Ocean, the ministry said.

China and Russia have regularly flown military aircraft inside the KADIZ since 2019, citing joint exercises.

The two countries are traditional allies of North Korea, with its perennially tense ties with the government in Seoul. They have also expanded their bilateral and defense ties since Russia's 2022 full-scale invasion of Ukraine.

South Korea deployed jets in November last year in response to Chinese and Russian jets entering the KADIZ, with similar incidents taking place twice in both 2023 and 2022. 

Edited by: Louis Oelofse