South Korea and Japan on High Alert as China and Russia Enter Defense Zone

South Korea and Japan scrambled fighter jets as two Chinese and four Russian military planes entered South Korea's air defense zone. The planes did not violate South Korea's territorial airspace, but their presence prompted the response. Japan also monitored the joint flights of Chinese and Russian bombers and fighters in the East China Sea. An Air Defense Identification Zone (ADIZ) is an area where countries can demand foreign aircraft to identify themselves, but it is not governed by international laws. Moscow does not recognize Korea's ADIZ, while Beijing argues that it is not territorial airspace.