JOINT BASE PEARL HARBOR-HICKAM, Hawaii - The Air Force says an F-16 flying from Japan to Alaska last July crashed at sea because a valve stopped fuel from reaching the engine.

An accident investigation report released by Pacific Air Forces in Hawaii on Tuesday says the jet's main fuel shut-off valve was partially closed for more than three minutes and fully closed for three minutes.

Investigators weren't able to determine why the valve closed because vital pieces of evidence weren't recovered from the ocean floor.

The F-16 with the 35th Fighter Squadron at Misawa Air Base crashed July 22 about 250 miles (400 kilometres) off the coast of Hokkaido, Japan's northernmost main island.

The pilot ejected safely and was retrieved after about six hours by a combined Japanese and U.S. rescue mission. He wasn't injured.

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