Scenarios: Bin Laden's secret years; where was he and who knew?

ISLAMABAD (Reuters) - U.S. investigators are trying to put together the pieces of Osama bin Laden's secret life in the hope of unearthing details of his global network of Islamist militants bent on attacking the West.

Key to that will be tracing his movements from the weeks after the September 11, 2001, attacks on the United States to last week, when U.S. special forces killed him after discovering him hiding in a compound in the Pakistani town of Abbottabad.

Efforts to trace his movements over the decade are likely to shed light on who helped him, and that could prove highly embarrassing to U.S. ally Pakistan which has rejected as absurd accusations it was either incompetent or playing a double game.

Following are some possible explanations for how bin Laden ended up under the noses of the Pakistani authorities, in a compound with high walls topped with barbed wire, a short distance from the country's top military academy.

HE WAS ON HIS OWN

Pakistan has rejected any suggestion of involvement in bin Laden's lost years. That would mean he was on his own and managed to slip into Pakistan from Afghanistan in late December 2001 undetected, and remained hidden with a handful of aides and relatives from the eyes of the authorities, including the pervasive security agencies.

Pakistani investigators, questioning bin Laden's three wives who were found in the compound after the May 2 raid, said the women had told them bin Laden had been hiding in the compound for the past five years, and previously he had spent two-and-a-half years in the nearby village of Chak Shah Mohammad. Reporters could find no trace of bin Laden there.

A move to Abbottabad in 2006 would suggest he felt compelled to leave wherever he had been. It was in January 2006 that the CIA began its campaign of attacks by missile-firing drone aircraft on militants sheltering in lawless Pashtun tribal lands on the Pakistani side of the Afghan border, with a deadly strike on Damadola village, in the Bajaur region.

Another possibility is that bin Laden felt compelled to move after an earthquake in October 2005 killed 73,000 people. The U.S. military and other Western armies sent forces to help with rescue efforts in northern mountains, including the Pakistani part of the Kashmir region where various militant groups operate. Had bin Laden been holed up in the disaster zone, he might have felt it safer to move somewhere like Abbottabad, which was not badly hit and not the focus of foreign attention.

Whatever his movements, the fact he went undetected for at least five years in Pakistan suggests an intelligence failure. Abbottabad is a garrison town where military commanders come and go.

Residents in the neighborhood thought the behavior of the occupants of the bin Laden compound strange, particularly that about 16 children living there were schooled at home and never allowed out on their own. Did such behavior never rouse the curiosity of security agents, especially those responsible for the safety of the top brass on their comings and goings to the nearby military academy?

PAKISTAN KNEW EVERYTHING

Analysts find it hard to believe Pakistani leaders were sheltering the chief of a group whose members were trying to kill them.

Former military leader and president Pervez Musharraf narrowly survived two bomb attacks carried out by al Qaeda-linked militants while his prime minister survived one. Security forces, including the main Inter-Services Intelligence (ISI) agency, have been repeatedly attacked by bin Laden's followers, losing thousands of men.

It seems inconceivable that there was any formal government decision to shelter bin Laden, especially one made by a civilian government that took power in 2008, or that government leaders had any clue about him.

But in a country that has been ruled by the military for more than half its 64 years of history, such sensitive issues are anyway the exclusive domain of the military/security establishment.

ROGUE OR RETIRED SECURITY AGENTS HELPED HIM

The truth almost undoubtedly lies somewhere in the murky void between the scenario that Pakistan authorities knew nothing and knew everything.

It's conceivable that in the fraught weeks after the September 11 attacks, the world's most wanted man slipped across the border from Afghanistan to escape U.S. bombs and someone decided it was in Pakistan's national interest to hold the "asset".

Security agents could have set up an independent team outside the chain of command to watch over the al Qaeda leader. That could have given Pakistan's security establishment the best of both worlds - plausible deniability and an asset of unmatched value.

Or rogue or retired security agents could have decided that in defiance of the country's official policy to join the United States in the global campaign against militancy, it was in Pakistan's national interest to hold him. They could have let the al Qaeda leader hide under the noses of the military, and under their watch, in the garrison town.

It was only a chance phone call, intercepted by a Pakistani security team probably with no idea of any link to bin Laden, or to his handlers, and passed on to the United States, that led the CIA on its secret mission to his lair.

WHY?

The answer to why some Pakistanis might have thought it wise to hold the man some of whose followers are battling the Pakistani state could probably be found in the country's obsessive suspicion of its nuclear-armed rival, India.

Pakistan has no interest in bin Laden's global holy war but the defense against perceived Indian aggression drives strategic thinking, and militants have regularly been used against India and its influence in the region.

No matter that some al Qaeda followers were battling Pakistan, if others were willing and able to fight India, perhaps it was seen as best to hold their inspirational leader.

Or perhaps some Pakistanis thought bin Laden could have been an ace to offer the United States the next time war with India loomed.

Or perhaps some Pakistanis thought U.S. engagement with Pakistan, its influence with India on Pakistan's behalf, and its billions of dollars in aid, would end once the Americans had caught their enemy number one.

(Editing by John Chalmers)