On the outskirts of the Pakistani capital lives a militant considered so powerful that Osama bin Laden consulted with him before issuing a fatwa to attack American interests.
Fazle-ur-Rahman Khalil heads Harakat-ul-Mujahedeen, a terrorist group closely aligned with al-Qaeda and a signatory to bin Laden's anti-US fatwa in 1998. Khalil has also dispatched fighters to India, Afghanistan, Somalia, Chechnya and Bosnia, was a confidante of bin Laden and hung out with 9/11 mastermind Khalid Sheikh Mohammed.
Pakistani authorities are clearly aware of Khalil's whereabouts. But they leave him alone, just as they tolerate other Kashmiri militant groups nurtured by the military and its intelligence agency to use against India.
Khalil is also useful to the authorities because of his unusually wide contacts among Pakistan's many militant groups, said a senior government official who is familiar with the security agencies and who spoke on condition he not be identified fearing repercussions.
Khalil's presence in an Islamabad suburb, confirmed to The Associated Press by Western officials in the region, underscores accusations that Pakistan is still playing a double game, fighting some militant groups while tolerating or supporting others, even after the solo US raid that killed bin Laden on May 2.
The US Congress, enraged that bin Laden found refuge for at least five years down the street from Pakistan's equivalent of West Point, has threatened to cut off the billions of dollars in aid being spent here.
Obama administration officials and US Army officers are trying to rebuild the relationship, considered vital to American hopes of negotiating an end to the Afghan war, but if anything the two sides appear to have drifted further apart in recent weeks.
Pakistan's intelligence service has arrested five Pakistanis who fed information to the CIA before the American raid that killed bin Laden, according to a Western official in Pakistan.
The group of detained Pakistanis included the owner of a safe house rented to the CIA to observe bin Laden's compound in the military town of Abbottabad, a US official said. The owner was detained along with a "handful" of other Pakistanis, said the official.
Also, CIA Director Leon Panetta confronted Pakistan's intelligence service about tipping off militants running bomb factories aimed at killing US soldiers in Afghanistan. Pakistan denied tipping them off. The militants belong to the Haqqani network, an Afghan Taliban faction that has ties to al-Qaeda.
Khalil's Harakat-ul-Mujahedeen, blamed for a deadly attack on the American Consulate in Karachi in 2002, has links to the Haqqanis and is considered a terrorist organization by the US. Hundreds of militants are thought to belong to his organization, though the strength of these groups are the links they share with each other, say analysts.
Khalil himself is not on any US wanted list. In the Islamabad suburb of Golra Sharif, he lives in a nondescript two-story compound that includes a seminary or religious school, hidden behind a traditional high wall protected by barbed wire.