Libya has sent all its known remaining nuclear weapons-related equipment to the US as part of a disarmament deal.
Libya revealed the extent of its nuclear programme late last year
A ship carrying 500 metric tons of equipment left Libya on Saturday for an undisclosed site in the US, White House spokesman Sean McCormack said.
He said long-range missiles and launchers were also part of the cargo.
The move follows Libya's surprise announcement in December that it was scrapping its weapons programmes in a bid to end its international isolation.
Secret talks had been held between Muammar Gaddafi's state and its old enemies - the US and the UK - and further improvements in relations have been made since.
The US has announced that talks will begin on Sunday with Libyan officials on retraining their weapons scientists.
The BBC's Rob Watson in Washington says the shipment is another extraordinary twist in the warming relations between the once-sworn enemies.
The shipment is said to includes Scud missiles and launchers
He adds that both the US and Libya are getting what they want - with Libya's isolation ending while Washington can point to the rewards on offer for countries ready to abandon their weapons of mass destruction.
In the space of the last week or so, the US has lifted restrictions banning Americans from visiting Libya and has given permission for a Libyan diplomatic presence in Washington.
In February, Mohammed Abdulrahman Shalgam became the first Libyan foreign minister to visit London since 1969.
Col Gaddafi told the Washington Post on Saturday that he was optimistic about better relations with the US, now that, as he put it, they were "able to talk".
The White House said the final shipment includes:
- centrifuge parts used to enrich uranium
- all equipment from Libya's former uranium conversion facility
- all of Libya's longer-range missiles, including five Scuds, and all associated equipment, including launchers.
Earlier shipments of nuclear weapons-related equipment were taken to the Oak Ridge National Laboratory in Tennessee, where the material is believed to have been destroyed.
Mr McCormack also reported that all of Libya's known chemical munitions had been destroyed and its stocks of mustard gas had been moved from insecure warehouses to a single, secure, facility.
The US, he said, would work with Libya to "achieve the
destruction and elimination of the actual agent itself".
Gaddafi's December move was hailed around the world
On Friday, Libya declared that it had a 20-ton stockpile of mustard gas in a full report on its chemical weapons programmes submitted to the UN.
The Libyans also detailed large amounts of chemicals used to make nerve gas.
The UN hailed the declaration as a major step towards eliminating Libya's weapons of mass destruction.
Most US trade restrictions still remain on Libya but American companies are now allowed to prepare for a return to Libya.
The US decision to ease punitive measures also followed Tripoli's clarification that it accepted responsibility for the Lockerbie bombing in 1988, over-riding comments by its prime minister who denied Libya had had any part in the attack.