Russian and Chinese fighter jets entered South Korea's air defense identification zone (KADIZ) last month without prior notice, a Seoul official claimed on Tuesday.
Two Russian planes flew into the KADIZ on March 24, just hours before Pyongyang test-fired an intercontinental ballistic missile into the East Sea, Yonhap News Agency quoted the official as saying.
A day earlier, the Chinese military fighter jet also entered the KADIZ near Ieo Islet, a submerged rock south of South Korea's southern resort island of Jeju. The area was where the air defense identification zones of South Korea and China overlapped, the official added.
The air defense zone is not territorial airspace, but is customary for foreign aircraft entering such zones to identify themselves to prevent accidental clashes.