John Brennan, the White House counter-terrorism chief, said that the assault force who attacked bin Laden's compound, would only have accepted surrender if they were 100 per cent sure that he was unarmed and "did not pose any type of threat whatsoever".
Speaking on Fox television, Mr Brennan said if US troops "were confident of that in terms of his not having an IED [improvised explosives device] on his body, his not having some type of hidden weapon or whatever".
A senior congressional aide who was briefed on the rules of engagement, said; "He would have had to have been naked for them to allow him to surrender".
A special forces officer told The Los Angeles Times: "The right of self-defence is never denied. If anyone feels in any way that there is a hostile threat in a case like this ... it can be a movement, or a failure to follow commands ... deadly force will be authorised. It's a judgment call.
"And these assaulters are some of the finest, most highly trained in discriminate shooting. They train for hostage rescue." (read more)