The U.S. Army has announced the grounding of all its nonessential flights in the wake of two separate helicopter crashes in the span of a month that claimed the lives of 12 servicemembers, reported the Daily Mail.

The Army is requiring all aviation units to undergo further training before returning to the skies.

Soldiers in the Reserves and National Guard will have until May 31 to complete this training, but active-duty service members will reportedly need to have it done by May 5.

The grounding, which does not apply to those undertaking critical missions, takes effect immediately.

Army Chief of Staff James McConville said the flight ban was "an important step to make certain we are doing everything possible to prevent accidents and protect our personnel."

The Alaska Accident

The most recent crash happened near the town of Healy, Alaska on Thursday, April 27, reported the Associated Press.

Three soldiers lost their lives when two helicopters crashed into each other, and another soldier suffered injuries.

The choppers were on their way to Fort Wainwright after completing a training mission in the Donnelly Training Area.

On Saturday, the Army named the deceased soldiers as Chief Warrant Officer 2 Kyle D. McKenna (28), Chief Warrant Officer 3 Christopher Robert Eramo (39), and Warrant Officer 1 Stewart Duane Wayment (32).

The injured soldier was not named, though officials did reveal he was in stable condition.

A source told the AP that the U.S. Army Combat Readiness Center has deployed a Safety Investigation Team to lead the probe into the crash.

The Kentucky Accident

This crash follows an accident in Kentucky in March that saw nine service members lose their lives, reported The Guardian.

On that occasion, a pair of Black Hawk medical evacuation helicopters collided during a nighttime training drill about 30 miles from Fort Campbell.

Officials shared that both helicopters involved in that accident crashed in a field. No one on the ground suffered injuries as a result.

A number of eyewitnesses in the locality saw the crash. One man said he "saw what looked like a firework went off in the sky."

There was also another military helicopter crash in Alaska in February of this year, though there were no fatalities that time.

On that occasion, an Apache chopper rolled shortly after takeoff, injuring two soldiers, The Guardian reported.