Japan's transport ministry says 2 Air Self-Defense Force fighter jets wrongly entered a runway at Naha airport in Okinawa, southwestern Japan, as a passenger plane was approaching to land.
Transport safety authorities are investigating the incident, which they say could have led to an accident.
Ministry officials say the incident involving the F-15 fighters occurred on Thursday evening.
The air traffic controller had instructed the jets to wait short of the runway as a Ryukyu Air Commuter plane approached from 5 kilometers away.
The 2 jets entered the runway regardless, forcing the controller to cancel landing permission for the passenger plane. The controller granted permission to land again after confirming that the ASDF fighters had left the runway.
The Ryuku Air Commuter plane landed safely 2 minutes later.
The ministry says there was no imminent risk of a collision, but that in the worst case scenario there could have been an accident.
Japan's Transport Safety Board is sending 4 inspectors to the airport on Saturday to find out what happened.