On April 20, 1978, Soviet air defense shot down Korean Air Lines Flight 902 (KAL 902) near Murmansk, Soviet Union, after the civilian aircraft violated Soviet airspace and failed to respond to Soviet ground control and interceptors. Soviet air defense initially identified it as part of the US air reconnaissance force, which carried out thousands of flights along Soviet borders annually at the time. Captain Alexander Bosov, pilot of the Sukhoi Su-15 that brought down Flight 902, saw Asian logogram characters on the tail of the Korean aircraft, and reported this to the ground control. Despite this, Vladimir Tsarkov, commander of the 21st Soviet Air Defense Corps, ordered Bosov to take down the plane, as the plane failed to respond to repeated orders to land, and was approaching the Soviet border with Finland.