Two United States Army attack helicopters crashed while on a training flight in Alaska on Thursday, the military said, the second such incident in less than a month.
The accident followed a similar incident in late March in which two US Army Blackhawk helicopters crashed during a training flight in Kentucky, killing all nine soldiers on board.
There have been multiple other crashes of US military aircraft in recent years, including another involving a Black Hawk that killed two Tennessee National Guardsmen during a training flight in Alabama in February.
Four US Marines were killed during NATO exercises in Norway last year when their V-22B Osprey aircraft went down, possibly after hitting a mountain, investigators said.
And two US Navy pilots were rescued after their T-45C Goshawk jet crashed during a training exercise in a residential neighbourhood near Fort Worth, Texas in 2021. The pilots ejected before the plane went down.