Two Japanese F-35A stealth fighter jets made emergency landings at a commercial airport in northern Japan on Monday, but there were no injuries or damage, officials said, Paralel.Az reports citing Associated Press.

The fighter jets were on a training flight from Misawa Air Base and landed safely at nearby Aomori Airport after one developed an unspecified mechanical problem and requested an emergency landing, airport officials said.

Japan’s Air Self Defense Force declined to provide details, including the cause of the emergency landing.

The airport said its runway was closed for about 20 minutes because of the emergency landing before operations returned to normal.

The incident is the latest in a series of problems involving flight training by Japan’s military.

In April, two Japanese navy SH-60K Seahawk helicopters crashed in the Pacific south of Tokyo after colliding during a night-time anti-submarine warfare training drill, killing one crew member and leaving seven others missing.

Last month, a C-2 transport aircraft carrying eight people made an emergency landing at a commercial airport in central Japan after a cockpit window slid open during a training flight. No damage or injuries were reported.