Describing his killing, General Caldwell says US troops had attempted to stop the vehicle in which Sheikh Mansur was travelling with two others.

He says when they kept driving they decided to fire at them from a helicopter that had been backing up soldiers on the ground.

General Caldwell says coalition forces were "following and tracking him for sometime as the intent was to capture him".

"When that proved something that was not able to be achieved by forces involved in that operation, they went ahead and used air assets to engage and destroy that vehicle," he said.

I gather from that description that we're not talking about a polite shot to the engine block by a sharpshooter with a Barret .50.