U.S. accepts blame for Canadians' deaths

WASHINGTON (CNN) -- The U.S. military has accepted full responsibility for the accidental April bombing that killed four Canadians and wounded eight others in Afghanistan.

The findings of a joint investigation released Friday could mean criminal charges for two U.S. pilots and discipline for superiors in the chain of command.

The fatal mistake occurred April 17 as two F-16s were returning from a mission over Afghanistan, and the lead F-16 pilot, Maj. William Umbach, saw what looked like fireworks coming from an area a few miles south of Kandahar, according to the report by U.S. and Canadian investigators.

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An AWACS reconnaissance plane gave the first F-16 permission to pinpoint the source of the fire, but denied a request from his wingman, Maj. Harry Schmidt, in a second F-16, to attack the position with a 20-mm cannon.

The AWACS told the wingman to "stand by" and requested more information, while directing him to "hold fire."

But the second F-16 radioed back that he was "rolling in, in self-defense," and dropped a 500-pound bomb on the friendly forces.

The Canadians were operating in an established training area and aircraft were restricted to altitudes above 10,000 feet to avoid any incidents.

Pentagon officials said Thursday the pilots were flying at 23,000 feet, well out of danger from small arms or anti-aircraft guns, and that the proper procedure would have been to clear the area to assess the threat.

"The board found the cause of the friendly fire incident to be the failure of the two pilots to exercise appropriate flight discipline, which resulted in a violation of the rules of engagement and inappropriate use of lethal force," said Lt. Gen. Michael Delong of the U.S. Central Command.

The U.S. military refused to comment on whether the pilots were briefed about the Canadian exercise, except to say that "failings within the pilot's immediate command structures" were contributing factors to the accident.

In a statement, the wingman's attorney, Air Force Capt. James Key said, "The pilot ... was completely unaware of the ... training area, much less that there was a live-fire exercise." He said the pilot "followed the proper defensive procedures" and "believed that his and the other pilot's lives were at stake."

Pentagon officials said while the pilots should have been told about the Canadian exercise, that does not excuse the violation of the rules of engagement.