Four Russian and two Chinese fighter jets had entered the South Korean air defense zone on Dec. 14, Yonhap news agency reported citing a source in the country's Joint Chiefs of Staff. South Korean fighter jets were scrambled to intercept the planes, which did not officially enter South Korea's airspace.
The air defense zone is not the same as territorially delineated airspace, which is protected by international law, but is established as a security mechanism for a country to monitor nearby foreign aircraft or missiles in advance.
Both Chinese and Russian military planes have been accused of engaging in aggressive behavior towards Western aircraft in international skies.
South Korea's military said this is not the first time that Russian and Chinese warplanes have jointly entered its air defense zone, having marked an intrusion in June, as well as in November 2022.