China said that the encroachment into South Korea’s air defense identification zone(KADIZ) by Chinese and Russian military planes without notice was in accordance with international law.

Beijing’s foreign ministry spokesperson, Mao Ning, said on Thursday that it was “routine flight activity” by Chinese military aircraft above international waters that is above reproach as it conformed to legal regulations.

Seoul's Joint Chiefs of Staff(JCS) said on Thursday that two Chinese and four Russian military planes entered the KADIZ from north of the eastern island of Ulleung at 11:53 a.m. before leaving the zone over the easternmost Dokdo islets 12:10 p.m.

The JCS noted that the aircraft stayed in the KADIZ for 17 minutes and did not violate South Korea’s airspace.

Although the issuance of a notification that military aircraft are entering another country's air defense identification zone is standard international practice, Chinese and Russian jets have entered the KADIZ a number of times without notice, citing combined exercises as the pretext.

The JCS said that it protested the incursion to Beijing through a direct military line.