US military grounds fleet of Osprey aircraft following deadly crash

The U.S. military announced Wednesday the grounding of all its Osprey CV-22 aircraft, one week after eight Air Force Special Operations Command service members died in a crash off the coast of Japan.

The decision to ground the entire fleet of Ospreys came after a preliminary investigation revealed that a material failure was the cause of the devastating crash — not a mistake by the crew.

The military said that the "standdown" of the Osprey CV-22 helicopters will "provide time and space" for a thorough investigation and to ensure safe return of operations.

In a release, the Air Force Special Operations Command said that the underlying cause of the failure is still unknown at this time.