U.S. and European intelligence officials increasingly believe active or retired Pakistani military or intelligence officials provided some measure of aid to al Qaeda leader Osama bin Laden, allowing him to stay hidden in a large compound just a mile from an elite military academy.
Reuters Abbottabad residents peer through the gates of the bin Laden compound on Wednesday.
The suspicions cast light on where the U.S. is expected to focus as it investigates who might have helped bin Laden hide in plain sight in Abbottabad, a town about 40 miles from the capital Islamabad.
Two senior U.S. officials and a high-level European military-intelligence official who have direct working knowledge of Pakistan's military intelligence agency, the Inter-Services Intelligence Directorate, say similar elements linked to the ISI have aided other Pakistan-based terror groups, the Haqqani militant network and Lashkar-e-Taiba.
"There's no doubt he was protected by some in the ISI," the European official said of bin Laden. The officials say they believe these ISI elements include some current and former intelligence and military operatives with long-standing ties to al Qaeda and other militant groups.
The officials didn't offer specific evidence, but pointed to the town's proximity to the capital and its high concentration of current and former military and intelligence officers. They said aid likely included intelligence tips to help keep bin Laden ahead of his American pursuers.
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But others in both the U.S. and Pakistan have cast doubt on whether Abbottabad would have provided a more hospitable refuge than other towns, or whether officials would have reason to believe bin Laden could be hiding there.
Details continued to emerge Wednesday that added to questions about what officials may have known. Abbottabad had come to the notice of Pakistani intelligence as a suspected hiding place for al Qaeda leaders as long ago as 2003, and was the focus of searches for top al Qaeda figures in years since.
In 2005, the man who was later identified as bin Laden's courier acquired the property in Abbottabad on which the compound was built, U.S. officials said Wednesday. The name he used, Arshad Khan, is the local alias he employed. It was this courier who, nearly six years later, eventually led the U.S. to the compound.
Pakistan denies it knew of bin Laden's whereabouts or sheltered him. Pakistani officials point out they passed the information about the 2003 search to their American counterparts.
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Anjum Naveed/Associated Press U.S. forces found Osama bin Laden at this compound in Abbottabad, Pakistan, about 40 miles outside Islamabad.
U.S. officials say intelligence cooperation with Pakistan has helped the U.S. carry out many critical operations but that the intelligence used in the raid that killed bin Laden early Monday local time came from American sources and intelligence.
In classified congressional briefings this week on the U.S. operation that killed bin Laden, senior national-security officials have told lawmakers they suspected Pakistan wasn't as forthcoming as it could have been about its intelligence on bin Laden, an official briefed on the exchanges said.
They also told lawmakers they were looking for evidence that elements within the ISI and the army played a direct or indirect role in protecting the al Qaeda leader, several officials said. Helping the effort will be the cache of computers, storage drives and other materials taken from bin Laden's residence.
The aftermath of the raid that killed bin Laden could have sweeping implications for the quickly deteriorating U.S. relationship with Pakistan—a longtime bulwark in U.S. efforts to fight terrorist groups—and on the U.S.-led war in neighboring Afghanistan.
Militants use havens in Pakistan to stage attacks against U.S. forces in Afghanistan. U.S. officials believe the war effort hinges on Pakistan doing far more to close the havens. The U.S. administration also worries what will happen to the tottering nuclear state if its economy collapses, as U.S. lawmakers challenge ongoing aid to Pakistan.
It remains unclear what could motivate those within Pakistan to help shelter bin Laden, and will remain so until the U.S. and European suspicions take clearer form. For a rogue element, sympathy with bin Laden could be enough. If more senior officials are implicated, that would suggest a desire to pacify radical elements who might otherwise turn their attention on Pakistani ruling elites.
Cooperation between the ISI and CIA has long ebbed and flowed, but had worsened even before the bin Laden discovery, largely triggered by the arrest earlier this year of a CIA contractor for shooting two Pakistanis. "Pakistan became paranoid about the agency's presence," a U.S. official said.
Underlining its displeasure, the ISI has this year moved to curtail the CIA's presence in the country, reflecting Pakistani fears that the U.S. spy agency had build up an extensive network of agents and informants to allow it to carry out unilateral operations against militants behind the ISI's back.
An ISI official Wednesday said Pakistani authorities in no way provided any support or cover for bin Laden in Pakistan, something everyone would have known was clearly unacceptable to the U.S.
"We need to have America on our side," the official said. "The best way to do it was to get bin Laden and hand him over."
One former intelligence official with extensive experience in Pakistan said the ISI would have responded immediately when the compound came under attack if it had been his protector.
U.S. officials say they don't believe that Pakistan's Army chief, Gen. Ashfaq Kayani, or ISI head, Lt. Gen. Ahmed Shuja Pasha, had knowledge of bin Laden's whereabouts or of secret assistance that may have been provided to him.
"The United States does not have any indication at this point that there was official Pakistani knowledge of bin Laden's whereabouts," a U.S. official said.
Neither Gen. Kayani nor Lt. Gen. Pasha were informed about the U.S. intelligence or the planned raid until after the U.S. helicopter-borne Navy Seal team carrying bin Laden's body exited Pakistani airspace, U.S. officials say.
Officials and experts are divided about whether Gen. Kayani and Lt. Gen. Pasha are aware of the activities of ISI personnel who may be based in isolated tribal outposts and have had longstanding ties with al Qaeda and the Taliban leaders.
ARSHAD ARBAB/European Pressphoto Agency Pakistani lawyers in Peshawar, Pakistan, offer funeral prayers for bin Laden.
The U.S. primarily deals with the ISI division responsible for counterterrorism, a former senior intelligence official said. That means ISI officials who work with the U.S. would be separate from ISI officials working with militants.
One senior U.S. defense official described the ISI as "highly compartmentalized," allowing networks of current and former operatives to act with relative autonomy and without the knowledge of their superiors.
U.S. officials say they have evidence that the Haqqani network, a militant group based in Pakistan's mountainous North Waziristan region, receives material support from the ISI in executing attacks against U.S. and North Atlantic Treaty Organization forces in neighboring Afghanistan. Lashkar-e-Taiba carried out a deadly 2008 assault in Mumbai.
In Abbottabad in December 2003, Pakistani intelligence officials mounted an unsuccessful strike to capture Abu Faraj al-Libbi, al Qaeda's No. 3, from a safe house in the town, according to Asad Munir, a former ISI official who oversaw the area at the time. In 2004, according to local news reports, Pakistani authorities arrested an Egyptian al Qaeda operative using Abbottabad as a base to plan attacks.
Abbottabad's recent history raises the question of whether the U.S. missed earlier signs that could have identified the town as an al Qaeda sanctuary. A senior U.S. official said Abbottabad was "a place we always looked" because "we always figured that Osama bin Laden would not be in a cave."
But others noted that it was one of many cities where al Qaeda and Taliban militants have hid, and one where Islamists wouldn't have a particularly sympathetic base.
"Abbottabad had never been a hotbed of Islamic fervor," said a former senior intelligence official. "It's never been the center of Islamic extremist activity or al Qaeda activity. There have been al Qaeda figures passing through from time to time."
Khalid Tanveer/Associated Press Anti-American protesters in Multan, Pakistan, question the raid.
Pakistani officials have been tight-lipped about what they found in the compound after American forces left. Pakistan has released no official accounting of how many people were taken into custody or how many bodies were found. Nor have military officials explained why soldiers didn't arrive on the scene of a 40-minute firefight that took place on the doorstep of Pakistan's military academy.
There are some conflicts between the U.S. and Pakistani accounts. U.S. officials say they left four bodies behind: three men and one woman. A Pakistani official said all four were men.
The Pakistani official said bin Laden's 12-year-old daughter, who is among those in Pakistani custody, told authorities the Americans took two people when they left, including bin Laden. U.S. officials say bin Laden's body was the only one removed from the scene.
—Siobhan Gorman, Jay Solomon and Tom Wright contributed to this article. Write to Matthew Rosenberg at matthew.rosenberg@wsj.com
