As the Gaddafi regime hangs by a thread the United States is becoming increasingly concerned about the fate of Libya’s weapons stockpiles.
US intelligence fears that Gaddafi may use the weaponry in a bloody last stand. But there is also the prospect of dangerous material falling into the hands of al Qaeda or other militant groups, even if the rebels consolidate victory.
Libya possesses a huge and varied arsenal including chemical agents and raw nuclear material as well as some 30,000 shoulder-fired rockets.
Weapons demolition teams have already been at work securing arms in rebel-held parts of the country, but their task is far from complete.
It is known that stocks of mustard gas and other substances are stored in drums at a site southeast of the capital Tripoli.
US intelligence is also aware that hundreds of tons of raw uranium yellowcake is housed in a nuclear facility to the east of Tripoli.
Libya signed up to the Organisation for the Prohibition of Chemical Weapons in 2010 and began a programme of destruction, which continued until the rebel uprising broke out in February, but the OPCW says much of the stock remains intact.
Mustard gas is a weapon that provokes burning blisters and death and the international community is desperate to keep this material off the black market, it is easy to transport and can spread fear and panic quickly.
As a result border security is a major concern and experts have been sent into Libya and neighbouring countries to tighten up frontiers and keep a potentially lethal cocktail of death agents safe and secure.