CIA director Leon Panetta said on Monday US intelligence officials did not know the exact whereabouts of all Pakistan's nuclear weapons but believed they were safe from the Taliban.
Speaking in Los Angeles, the Central Intelligence Agency chief said Pakistan's nuclear arsenal was "pretty secure" amid concerns that the weapons could possibly fall into the hands of Taliban insurgents.
"We don't have frankly the intelligence to know where they are all located but we do track the Pakistanis," Panetta said when asked if the US knew where Pakistan's nuclear weapons were located.
"Right now we are confident that the Pakistanis do have a pretty secure approach to trying to protect these weapons. But it is something that we continue to watch because obviously the last thing we want is for the Taliban to have access to nuclear weapons in Pakistan."
Pakistan forces have been locked in an offensive with Taliban fighters in the country for several weeks.
The fighting comes amid intense US pressure to crack down on militants in the northwest of the country which Washington says pose the most serious terrorist threat to the West.
Panetta was speaking at a luncheon hosted by the non-partisan Pacific Council on International Policy think tank in Los Angeles.