Two former militant commanders and one senior fighter who have received support from the ISI for years said they were convinced that the ISI played a part in sheltering Bin Laden. Because of their covert existence, they spoke on the condition that their names not be used.

One of the commanders belonged to Harakat. The other said he had fought as a guerrilla and trained others for 15 years while on the payroll of the Pakistani military, until he quit a few years ago. He said that he had met Bin Laden twice.

Meetings in Tribal Areas

In the spring of 2003, Bin Laden, accompanied by a personal guard unit of Arab and Chechen fighters, arrived unexpectedly at a gathering of 80 to 90 militants at a village in the Shawal mountain range of North Waziristan, in Pakistan’s tribal areas, the former commander said. He met Bin Laden briefly inside a house; he said he knew it was him because they had met before, in Afghanistan before the Sept. 11, 2001, terrorist attacks.

The encounter in North Waziristan occurred before the American campaign of drone aircraft strikes, which began in 2004, made it unsafe for militants to gather in the area in large numbers. For about three years before the American drone campaign, Bin Laden was moving from place to place in Pakistan’s mountainous tribal areas, the commander said.

The United States had small Special Operations units and C.I.A. operatives working with Pakistani security forces to track Qaeda members at that time. At some point Bin Laden went deeper underground. That is when the commander speculated that the Qaeda leader was moved to a safe house in a city, though he did not say he knew that Bin Laden had gone to Abbottabad.

He and the other commander, who spent 10 years with Harakat, offered no proof of their belief that Bin Laden was under Pakistani military protection. But their views were informed by their years of work with the ISI and their knowledge of how the spy agency routinely handled militant leaders it considered assets — placing them under protective custody in cities, often close to military installations.

The treatment amounts to a kind of house arrest, to ensure both the security of the asset and his low profile to avoid embarrassment to his protectors.