The Pentagon is working on contingency plans to prevent Pakistan's formidable nuclear arsenal from falling into the hands of Islamist radicals and insisted yesterday that the arsenal was safe in spite of the upheaval in the aftermath of the assassination of Benazir Bhutto.
Pentagon spokesman Col Gary Keck said: "At this time, we have no need for concern."
However, the Bush administration is less confident about the future. The US administration has spent $100 million (€68 million) over the past six years on improving the security of Pakistan's nuclear programme.
One of the contingency plans would involve US special forces working with Pakistan's military and intelligence services to spirit away any weapons at imminent risk. However, the US cannot be confident that the Pakistan military would co-operate at such a time.
In spite of US aid to help with security, the Pakistan government has remained suspicious of US intentions, fearing that it might plant devices capable of neutralising the weapons.
As a result, Pakistan has withheld information about the location of all its arsenal and other specifics.
Pakistan's nuclear scientists and technicians go to the US for training. It carried out its first nuclear test in 1998 and claims to have about 80 to 120 warheads. It also has many decoys to confuse would-be thieves.
Pakistan's nuclear weapons are believed to be stored in bunkers in about half-a-dozen military bases and, to provide a degree of safety, the components are understood to be kept separately.