The U.S. is sending an F-35B squadron from Yuma to a Marine Corps Air Station in Japan.

The Marine Fighter Attack Squadron 121 left Yuma for Iwakuni, Japan on Monday.

According to a statement from the 3rd Marine Aircraft Wing in Miramar, California, the move marks a significant milestone in the F-35B program.

The squadron has roughly 300 personnel and the relocation is a permanent change of station. About 4,000 marines and sailors, and 2,000 civilian employees work at Marine Corps Station Yuma.