The U.S. fighter pilot who mistakenly bombed and killed four Canadian soldiers in Afghanistan in 2002 has talked about the incident on television for the first time.

Maj. Harry Schmidt was one of two National Guard pilots who attacked Canadian troops carrying out a night-time, live-fire military exercise near Kandahar on April 18, 2002.

In an interview with Dateline NBC that aired Sunday, Schmidt relived that night.

"Every time you go into combat, you have to be prepared to destroy something or take a life ... but you're never prepared for it to be someone from your own forces," he said.

When he and Maj. William Umbach flew high over the Afghan desert, Schmidt saw flashes on the ground and thought it was enemy artillery fire.

"I thought we had been ambushed at the time," he told NBC. "...If you witnessed a hostile act, it's an order to defend yourself."

'I remember praying all the way home'

The program aired previously released cockpit recordings of conversations between the pilots and ground control. The two pilots describe what they see, then Schmidt tells them he's "rolling in, in self-defence."

Against the orders of air controllers, he drops the 225-kilogram bomb that injured six Canadians and killed Pte. Richard Green, Pte. Nathan Smith, Cpl. Ainsworth Dyer and Sgt. Marc Léger.

"When the call came that there might be friendlies at Kandahar, I remember my heart sunk."

"When the call came that there might be friendlies at Kandahar, I remember my heart sunk and I remember praying all the way home that they were not our forces," Schmidt remembered.

He said that when he got back to the camp and was told he killed four allied soldiers, he dropped to his knees.

"I was just torn apart," he said.

Military defends Schmidt's punishment

After returning from Afghanistan, Schmidt was originally charged with manslaughter and faced a court martial, which could have sent him to prison for six months.

The case was later shifted out of the air force's criminal trial system. Schmidt was found guilty of dereliction of duty, reprimanded and fined $5,600 US in pay at a military hearing on July 6, 2004.

In the reprimand, Lt.-Gen. Bruce Carlson, who handed down the verdict, wrote that Schmidt "acted shamefully ...exhibiting arrogance and a lack of flight discipline."

Schmidt, a decorated navy pilot and former instructor at the Navy's "Top Gun" fighter pilot school, appealed but lost.

He lost his flying privileges, while Umbach quietly agreed to accept a reprimand and retire from the air force.

Col. John Odom – who led the prosecution against Schmidt and Umbach – told NBC that the proper actions for pilots in that situation would have been to fly away and await orders.

"The evidence from the tape screams that this was not an individual who was truly defending," he said.

Deaths left 'huge hole' in families, Schmidt says

Schmidt said he is a scapegoat for the military's failure to notify the pilots that there were Canadians in the area.

He has said his punishment was less about justice than about a military public-relations campaign aimed at appeasing an important ally.

'They didn't try to fix the problem. They fixed the blame."

"They didn't try to fix the problem," he told NBC. "They fixed the blame."

Schmidt has apologized for the accident but never for his role in it.

In the interview with NBC, he passed on a message to the families of the Canadian victims.

"There's a huge hole in those families and I want to tell them I understand that. I hope they know that I am truly sorry that the accident happened."

But Richard and Claire Léger, whose lost their son Marc in the "friendly fire" incident, couldn't quell a bit of anger as they watched the program from their home in Stittsville, Ont.

"You don't drop a 500-pound bomb just because you want to be a hero," Richard Léger told CBC News.