The U.S. Air Force has dropped criminal charges against the two US fighter pilots who mistakenly bombed and killed four Canadian soldiers in Afghanistan last year.

The Pilots Major Harry Schmidt and William Umbach had faced more than 60 years in prison if they were convicted on manslaughter, aggravated assault and dereliction in the line of duty.

But now the Air Force is now recommending the pilots face “administrative sanctions.”

This comes despite the findings of a joint US-Canadian investigation, which said the two pilots were at fault for the deaths.

The Canadian troops were training near the southern Afghan city of Kandahar on April, 17 2002 when they were bombed and killed.

The pilots reported what they believed to be enemy activity and requested permission to fire. US air controllers never gave permission but they dropped a 500-pound laser guided bomb on the target.