A South Korean Air Force official said that five Russian Air Force planes crossed into the Korea Air Defense Identification Zone (KADIZ) over the East Sea early this month. The official said that two TU-95 long-distance strategic bombers, two SU-27 fighter jets and an A-50 airborne early warning and control aircraft from Russia intruded more than 50 kilometers into the Korea Air Defense Identification Zone on February eighth. They reportedly left after Korean fighter jets arrived in the area, Korea\'s (KBS World) website reported Monday. . The Korean military issued several warning broadcasts and sent out ten fighter jets including six F-15Ks for an interception flight to drive away the Russian aircraft. The official believes the Russian planes first flew into Japan\'s Air Defense Identification Zone and were blocked by Japan\'s Air Self-Defense Force, so they changed course and entered Korea\'s zone. The intrusion by Russian aircraft occurs several times a year but Korean military authorities are looking into the reasons as it\'s the first time the planes have intruded this far into the Korean zone.