The US Army has reportedly grounded around 1,100 helicopters for five days after a number of helicopter crashes since October.
The grounded helicopters include Boeing AH-64 Apaches, CH-47 Chinooks, and Sikorsky UH-60 Black Hawks.
The grounding order for helicopter fleets at 11 bases is said to be focused on reviewing safety procedures.
US Army Forces commanding general Robert Abrams said: "I have a duty to ensure that we are doing all that we can to prevent loss of life and aviation accidents, and that is why we're standing down to review our procedures and reaffirm our commitment to operating our aircraft safely and effectively."
According to statistics from the Army Safety Center, 15 helicopter accidents have occurred in the past nine weeks.
The statistics also showed that around eight soldiers were killed in crashes since October, while only two people were killed in the two preceding fiscal years.
In November, the AH-64 Apache helicopter crashed nearly 50 miles east of Camp Humphreys in South Korea, killing two pilots on board.
The accident occurred during a routine training mission, and is currently being investigated.
Abrams added: "We cannot allow tragedy to pass unacknowledged.
"We must do whatever is needed to make certain that our soldiers are training and operating safely."