The Obama administration on Tuesday altered its account of the killing of Osama bin Laden, making clear for the first time that the Al Qaeda leader was unarmed when he was confronted and shot dead by US commandos.

White House Spokesman Jay Carney released a revised narrative of the 40-minute secret operation. He said the US Navy SEALs encountered hostile fire almost immediately upon arriving at bin Laden’s compound in Pakistan. They returned fire, killing two men and a woman who was apparently caught in the crossfire.

During a room-to-room search of the main house, US forces encountered bin Laden in an upstairs bedroom. When the commandos entered the room, bin Laden’s wife – who was unarmed – charged one of them. She was shot in the leg, but was not killed.

Bin Laden was fatally shot in the chest and in the head.

Carney said bin Laden “resisted” US forces, but the press secretary did not explain what constituted his resistance.

“Resistance does not require a firearm,” he said.

Earlier statements by administration officials had suggested bin Laden was armed and actively engaged in a firefight with the SEALs. According to Carney, those statements were not accurate.

The new account is far less dramatic than the original version. It is likely to raise questions about whether the US mission was a targeted killing of bin Laden rather than a mission to capture or kill him.

On Monday, John Brennan, assistant to the president for homeland security, told members of the press that US forces were prepared to take bin Laden prisoner. “If we had the opportunity to take him alive, we would have done that,” Mr. Brennan said.

“We had discussed that extensively in a number of meetings in the White House and with the president,” he said. “The concern was that bin Laden would oppose any type of capture operation.”

Brennan added: “Indeed, he did. There was a firefight.”

But it is unclear what role, if any, bin Laden played in the firefight. It is also unclear why, since bin Laden was unarmed, the decision was made on the scene to kill him rather than attempt to capture him.

“He resisted,” Carney said, offering no further details.

“The US personnel on the ground handled themselves with the utmost professionalism,” Carney added. “And [bin Laden] was killed in an operation because of the resistance that he – that they met.”

The fact that bin Laden was unarmed when he was shot and killed does not undermine the legality of the US military operation, according to legal experts.

Under the law of war, the commander of Al Qaeda was a legitimate military target. Members of the US assault team couldn’t know what bin Laden might attempt when cornered in his home.

By way of contrast, the standard used by law enforcement officers in the United States differs from the law of war. It is unclear, from the details now released by the White House, whether bin Laden’s actions would have posed a significant enough threat to justify the use of lethal force by arresting police officers.

But the raid on the bin Laden compound was not a law enforcement operation. It was a projection of US military force to “kill or capture” the world’s most wanted terrorist.

Although some critics have branded the US operation an “execution,” the American public overwhelmingly supports it. Nine in 10 Americans said they approved of the raid on bin Laden’s compound, according to a Gallup poll.

The same poll showed 33 percent of respondents would have preferred capturing bin Laden alive, while 60 percent said it was better for the US that he was killed during the operation.