US says bin Laden unarmed when shot dead

Osama bin Laden was unarmed when US special forces shot and killed him, the White House said, as it vowed to "get to the bottom" of whether Pakistan helped the al Qaeda leader elude a 10-year manhunt, even as Islamabad denied it gave shelter to him.

The White House also released more details about the killing of the world's most-wanted man, including that bin Laden was unarmed when he was shot at least once in the head by a US commando.

President Barack Obama's press secretary, Jay Carney, insisted the al Qaeda leader resisted -- although he would not say how -- when US forces stormed his compound north of Islamabad and engaged in a firefight there. Officials were still debating whether to release a "gruesome" picture of his body. 

Washington kept Pakistani officials in the dark about the special forces assault carried out on Monday, fearing they might "alert the targets" and jeopardize the mission, which ended with bin Laden's death, CIA Director Leon Panetta told Time magazine.

The revelation that bin Laden had holed up in a fortified compound in the military garrison town of Abbottabad, possibly for five to six years, prompted many US lawmakers to demand a review of the billions of dollars in aid Washington gives to nuclear-armed Pakistan. 

Pakistani President Asif Ali Zardari, issuing his first response to questions about how bin Laden was able to live undetected for so long near the capital Islamabad, did little to dispel suspicions.

"Some in the US press have suggested that Pakistan lacked vitality in its pursuit of terrorism, or worse yet that we were disingenuous and actually protected the terrorists we claimed to be pursuing," Zardari wrote in the Washington Post. "Such baseless speculation ... doesn't reflect fact." 

It was the first substantive public comment by any Pakistani leader on the airborne raid that killed the al Qaeda leader, who had become the face of Islamist militancy since masterminding the September 11, 2001 attacks on the United States.

Pakistan has come under intense international scrutiny since bin Laden's death, with questions on whether its security agencies were too incompetent to catch him or knew all along where he was hiding, and even whether they were complicit. 

"It would be premature to rule out the possibility that there were some individuals inside of Pakistan, including within the official Pakistani establishment, who might have been aware of this," White House counterterrorism chief John Brennan told National Public Radio.

"We're not accusing anybody at this point, but we want to make sure we get to the bottom of this," he said. 

Reflecting a US-Pakistani alliance strained by years of mistrust, Islamabad was not told about the raid until after all US aircraft were out of Pakistani airspace.

At the same time, killing bin Laden -- who became the epitome of evil for many Americans as architect of the 2001 attacks on New York and Washington -- has given Obama a popularity boost at home where his standing had been eroded by economic woes and high gasoline prices. 

About four in 10 Americans say their opinion of Obama improved after he ordered the bin Laden raid. But the bump in his ratings could be short-lived as voters focus again on domestic concerns crucial to his 2012 re-election prospects.

Obama may face more pressure to speed the planned withdrawal this July of some US forces from the unpopular war in Afghanistan.