Q&A: Bin Laden
The killing of Osama Bin Laden by US special forces in Pakistan has raised a number of questions - and not all of them have clear answers.
How was Bin Laden tracked down?
The hunt for America's most-wanted man was conducted over many years. Bin Laden was found through one of his personal couriers. Following investigations by the CIA and other US intelligence agencies, the courier was identified in 2007.
In mid-2010 he was tracked down to a large compound in Abbottabad, home to Pakistan's leading military academy, north-east of the capital Islamabad.
In February 2011 it was determined that there was "sound intelligence" that Bin Laden was living in Abbottabad with several family members.
Why are there different accounts of Bin Laden's death?
The operation was carried out by members of the US Navy Seals flown by helicopter from neighbouring Afghanistan, who fought their way into the compound.
The US has offered differing accounts of the killing of Bin Laden. Originally, officials said the al-Qaeda chief had "participated" in a firefight when he was shot dead.
On Tuesday, the White House corrected this, saying Bin Laden was unarmed. But it still insisted that he was resisting capture - although it is unclear exactly how he did so.
The latest account reported by the New York Times and the Associated Press cites US officials as saying that just one person in the compound was armed and fired a shot.
The president's spokesman suggested the initial confusion was the result of trying to provide a great deal of information in haste. But the shifting narrative will encourage those who doubt the official version of events.
How much scepticism is there?
Conspiracy theories began to circulate within minutes of the death being announced.
Blogs, forum and web pages - including a Facebook group entitled "Osama Bin Laden not dead" - are rife with suggestions that the US government faked the raid.
Correspondents say that many people in Pakistan doubt that he has been killed. And in a debate run by the BBC's Asian Network on Monday, some British Muslims also expressed scepticism.
"No body?," questioned one contributor. "I don't believe the Americans due to lack of evidence."
President Obama said: "There are going to be some folks who deny it. The fact of the matter is, you won't see Bin Laden walking on this Earth again."
Why has the US not released any pictures of the body?
The US is well aware of the pressure to provide proof of death.
Indeed US media have said that one of the reasons President Obama decided on a commando operation to kill Bin Laden rather than a bombing raid was to have positive identification of the body.
Officials say that DNA tests carried out on the remains showed a "virtually 100%" match with the DNA of Bin Laden's relatives.
Afterwards the body was being buried at sea. US officials said this was to avoid his grave becoming a shrine.
US officials had been discussing whether to publish pictures of Bin Laden's body to counter conspiracy theories that he did not die.
But President Obama eventually decided not to release the photos, saying: "We don't trot out this stuff as trophies."
He also said the images could inflame sensitivities.
"It is important for us to make sure that very graphic photos of somebody who was shot in the head are not floating around as an incitement to additional violence, as a propaganda tool. That's not who we are," he said.
However, some photos purporting to show the aftermath of the raid have been published by Reuters. They are very graphic - showing disfigured dead bodies, and the identity of those pictured has not been confirmed. They have been republished on the Guardian website.
Was Pakistan involved in the operation?
The US insists it planned and carried out the raid alone, and only notified the Pakistanis after the event.
The reason, one US official told reporters, was that "it was essential to the security of the operation and our personnel that only a very small group of people inside our own government knew of the operation".
But some commentators find it hard to believe that US aircraft could have penetrated deep into Pakistan, apparently evading air defences, without the army's knowledge.
A Pakistani intelligence official told the BBC off the record that Pakistan was informed that a raid was under way against an unidentified "high value" target, once US helicopters entered Pakistani air space.
Did the Pakistani army know Bin Laden was living close by?
Pakistani officials say they had no idea, despite the conspicuousness of the compound.
Completed in 2005, it is much larger than other homes in the area, and surrounded by high walls topped with barbed wire.
Many analysts are asking how a huge mansion with heavy security could have been built in a major garrison town, and occupied by Bin Laden, without anyone in the army noticing.
Bin Laden's Yemeni wife, thought to have been shot in the leg during the raid, said she had been living there with the al-Qaeda leader for five years.
The hunt has fuelled long-standing suspicions that some members of the intelligence arm of the Pakistan military - the ISI - are protecting militant leaders, a charge denied by Pakistan.
Asked why they had not checked out the building, an ISI official told the BBC that the compound had been raided when the house was under construction because the authorities believed al-Qaeda operative Abu Faraj al-Libbi was there.
But since then, he said, the house had not been on the ISI's radar and that the agency was extremely embarrassed by its intelligence failure.
Was the killing of Bin Laden legal?
The use of deadly force against Bin Laden, who was said to be unarmed, is unlikely to be challenged in an American court, but the US has already sought to defend its position on legal grounds.
US Attorney General Eric Holder said the acts taken were "lawful, legitimate and appropriate in every way".
US legal experts point to the fact that the US had declared itself to be in armed conflict with al-Qaeda.
Kenneth Anderson, a fellow in national security and law at the Hoover Institution, told Reuters: "It's lawful for the United States to be going after Bin Laden if for no other reason than he launched an attack against the US."
Other legal experts questioned whether this would stand up under international law.
Targeted killings under US law remain a disputed area.
US executive order 12333, signed by President Ronald Reagan, says: "No person employed by or acting on behalf of the United States government shall engage in, or conspire to engage in, assassination."
However, the term assassination has never been fully defined and some US legal advisers have sought to argue it does not apply in conflict situations.
State department legal adviser Harold Koh, quoted by Mr Anderson, said in March: "Under domestic law, the use of lawful weapons systems - consistent with the applicable laws of war - for precision targeting of specific high-level belligerent leaders when acting in self-defence or during an armed conflict is not unlawful, and hence does not constitute 'assassination'."
Profs William C Banks and Peter Raven-Hansen, writing in the University of Richmond Law Review, also argue it does not apply to figures such as Bin Laden, nor when the US is "in hostilities such as the Gulf War or war on those responsible for the 11 September attacks".
"The targeted killing of terrorists is therefore not unlawful," they conclude.
Mindful of its need to stress the military nature of the killing and the need to abide by conventions, the US has also said that Bin Laden presented a clear danger to its troops.
CIA director Leon Panetta said: "Obviously, under the rules of engagement, if he had in fact thrown up his hands, surrendered and didn't appear to be representing any kind of threat, then they were to capture him. But they had full authority to kill him."
British law professor Philippe Sands QC, of University College London, says the US can certainly argue that it was entitled to take action to protect its citizens against a deadly enemy.
"International law recognises that there are exceptional circumstances where necessity precludes wrongfulness, and this will be said to be one of those cases," Mr Sands told the BBC.
But Mr Sands says that what Pakistan knew and authorised, and what happened when the commandos confronted Bin Laden, will need to be known before the legal situation of the raid becomes clear.
UN High Commissioner for Human Rights Navi Pillay has called for more information and stressed international law must be respected - but accepted that taking Bin Laden alive was always likely to be difficult.