WASHINGTON — U.S. commandos who attacked Osama bin Laden’s compound were operating under rules of engagement that all but assured the Qaida leader would be killed, officials acknowledged as they backed away from their initial account that bin Laden had been armed and used a woman as a human shield.

After saying Monday that the American operatives who raided the compound had orders to capture bin Laden if he gave himself up, U.S. officials on Tuesday disclosed an important qualifier: the assault force was told to accept a surrender only if they could be sure he didn’t have a bomb hidden under his clothing and posed no other danger.

Bin Laden could have surrendered only "if he did not pose any type of threat whatsoever," White House counterterrorism chief John Brennan said on Fox television, and if U.S. 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."

Added a senior congressional aide briefed on the rules of engagement: "He would have had to have been naked for them to allow him to surrender."

Once troops exchanged fire with bin Laden allies living in the compound — three men were killed, in addition to the Qaida leader — the chances of a surrender were almost nil, experts say.

The surrender issues was one of several on which administration officials shifted ground. At the White House, Spokesman Jay Carney read a Pentagon "narrative" of the tense minutes at the compound in Abbottabad that he said was intended to correct information that had been released "in great haste" by Brennan the day before. Brennan had said bin Laden was armed, "engaged in a firefight" with U.S. forces and shielded himself behind a woman.

"In the room with bin Laden, a woman — bin Laden’s wife — rushed the U.S. assaulter and was shot in the leg but not killed," Carney said. "Bin Laden was then shot and killed. He was not armed."

CIA Director Leon Panetta said in an interview on PBS television Tuesday that he did not believe bin Laden had a chance to speak before he was shot in the face and killed.

"To be frank, I don’t think he had a lot of time to say anything," Panetta said.

Nonetheless, officials strongly defended the decision to shoot. "The right of self defense is never denied," said a Special Forces officer interviewed by telephone who was not authorized to speak publicly.

"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 authorized. It’s a judgment call. And these assaulters are some of the finest most highly-trained in discriminate shooting. They train for hostage rescue."

The CIA has had grim experience with concealed suicide vests: In December 2009, a Jordanian doctor the CIA believed was their agent blew himself up with vest, killing 7 CIA officers who had come to greet him at a base in Khost, Afghanistan.

Carney also said officials were still mulling the release of a "gruesome" photograph of a dead bin Laden. Officials understand that some people will not believe bin Laden is dead without seeing the photograph, but they are concerned about the "sensitivity" of the image.

He added that the White House stood by its claim on Monday that bin Laden had resisted capture, but said that "resistance does not require a firearm."

Asked how the White House had gotten the initial story wrong, Carney said that government officials had been rushing to release information about a complex, fast-moving operation.

"We provided a great deal of information in great haste in order to inform you, and through you the American public, about the operation and how it transpired," he said. "And obviously some of the information came in piece by piece and is being reviewed and updated and elaborated on."

One of the other people killed in the raid is believed to be bin Laden’s son and the other two dead men were described as brothers who are the listed owners of the compound, one of whom was the Qaida courier who unwittingly led the CIA to bin Laden. The dead woman is the wife of the courier, U.S. officials said.

Officials said they left the other residents, mostly women and children, at the compound.

Obama’s decision to order a surgical raid continued to draw praise on Capitol Hill from Republicans and Democrats.

"They could have sent a Predator with hellfire missiles and killed everyone in the place. They didn’t do it," said Sen. Dianne Feinstein, D-Calif., who chairs the intelligence committee. "It was a very gutsy mission."

If bin Laden had been taken alive it would have posed myriad complications.

The U.S. likely would have faced questions about the legality of having snatched a prisoner from a sovereign country without that country’s permission and whether to treat him as an enemy combatant or pursue a criminal prosecution.

Panetta told Congress last month that bin Laden probably would have been taken first to Bagram air base in Afghanistan and then Guantanamo, an uncomfortable chain of events for an administration that promised to close Guantanamo.And any legal proceeding, whether criminal or military, would have afforded the world’s most famous terrorist leader a global platform.

U.S. officials also disclosed new details of bin Laden’s activities while hiding in his Abbottabad compound. Bin Laden was removed from day to day operations of the terrorist network he had founded. But he continued to secretly send strategic guidance to affiliate groups scattered around the globe, the officials said.

Early this year, for example, bin Laden dispatched written messages by courier to al-Qaida franchises in Iraq, Yemen and Algeria, according to a three current and former U.S. officials who are familiar with the intelligence and who spoke on condition of anonymity.

"Bin Laden’s guidance was, ‘Remember, Americans are the primary enemy now. Don’t get bogged down in local fights,’" said one official.

He said the messages probably were designed to silence restive factions within the affiliates who wanted to join forces with local insurgencies against governments.

The official said bin Laden appeared particularly worried about attacks launched by an Algerian-based group, al-Qaida in the Maghreb, in North Africa.

Officials said the messages suggest that bin Laden was concerned that without his direction, the far-flung franchises could lose their common purpose against the West, and therefore diminish al-Qaida’s strategic power.

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Peter Nicholas of the Tribune Washington Bureau contributed to this article