The US military is grounding all of its 'widow-maker' Osprey V-22 helicopters after a crash in Japan killed 8 airmen

• The US military says it's grounding all of its Osprey helicopters.
• Last week, the aircraft crashed near Japan and killed eight US airmen.

The US military said on Wednesday that it is grounding its entire fleet of Osprey V-22 helicopters.

The announcement came after eight US airmen were killed when the aircraft crashed off the southern coast of Japan last week.

The Air Force Special Operations Command said in a statement on Wednesday that Lt. Gen. Tony Bauernfeind "directed an operational standdown" to "mitigate risk while the investigation continues."

"Preliminary investigation information indicates a potential materiel failure caused the mishap, but the underlying cause of the failure is unknown at this time," the statement continued.

The Naval Air Systems Command said in a separate statement on Wednesday that it is also grounding all its Ospreys "out of an abundance of caution."

"While the mishap remains under investigation, we are implementing additional risk mitigation controls to ensure the safety of our service members," their statement read.

This is not the first time the Osprey, which can function both as a helicopter and a turboprop aircraft, has been grounded.

In August 2022, the Air Force Special Operations Command said it grounded its CV-22 Ospreys because of an "increased number of safety incidents" involving the aircraft's clutch.

Then in February, all three services grounded some of their Ospreys to replace a clutch-related component.

Aircraft manufacturer Boeing said it's delivered at least 400 Ospreys, with most of them being used by the US military, per Reuters.

The Osprey holds the infamous moniker "widow-maker" after it was involved in a series of crashes.

Three US Marines were killed in August when an Osprey crashed during a training exercise in northern Australia. The aircraft was also involved in two separate crashes in California and Norway last year, where a total of nine US Marines were killed.