(Washington) The US Army decided on Friday to ground its aircraft for 24 hours, except for essential missions, after the crash of four helicopters in a month.

US Army Chief General James McConville “ordered an air travel freeze following two fatal crashes” Thursday in Alaska and late March in Kentucky, which killed three and nine respectively, according to a report. communicated.

Every active Army unit must enforce the 24-hour flight suspension next week.

“This decision bans all Army pilots from flying, except those on essential missions, until they complete necessary training,” the military added.

Three American soldiers died and another was injured Thursday in the mid-air collision of two Apache attack helicopters, returning from training in Alaska.

In late March, nine soldiers died when two Black Hawk helicopters crashed during a nighttime flying exercise in Kentucky.