North Korea's air force says Japan's E-767 surveillance aircraft conducted the aerial espionage near a missile site on its northeast
coast Wednesday and Thursday.
Pyongyang is threatening to shoot down any Japanese planes that intrude into its airspace.
The country's official Korean Central News Agency says North Korea's air force will ``mercilessly shoot down any plane intruding
into the territorial air of the (North) even 0.001 millimeter.''
The threat against Japanese alleged aerial espionage is rare as the North has regularly complained of U.S. spy missions over its airspace.
The North also has designated a no-sail zone off its east coast from June 25 to July 10 for military drills, raising concerns that it might test-fire short- or mid-range missiles in the coming days.