The CIA says Osama Bin Laden is isolated from the day-to-day operations of al-Qaeda, but that the organisation is still the greatest threat to the US, BBC reported.
CIA director Michael Hayden said the Saudi militant was probably hiding in the tribal area of north-west Pakistan.
Mr Hayden said Bin Laden was "putting a lot of energy into his own survival" and that his capture remained the US government's top priority.
But he warned that al-Qaeda was still spreading in Africa and the Mid-East.
In a speech to the Atlantic Council on Thursday, Mr Hayden said: "[Bin Laden] is putting a lot of energy into his own survival, a lot of energy into his own security."
"In fact, he appears to be largely isolated from the day-to-day operations of the organisation he nominally heads."
However, Gen Hayden added: "If there is a major strike on this country, it will bear the fingerprints of al-Qaeda."
The CIA believes progress has been made in curbing al-Qaeda's activities in the Philippines, Indonesia, Saudi Arabia and Iraq.
However, Mr Hayden said other areas were showing an increase in activity, including East Africa, The Maghreb, Yemen and Pakistan
Nevertheless, the CIA chief said the hunt for Bin Laden remained the top priority of the US security forces.
"His death or capture clearly would have a significant impact on the confidence of his followers - both core al-Qaeda and unaffiliated extremists throughout the world," he said.