British Prime Minister David Cameron has spent almost three hours in talks with United States President Barack Obama.
It is the first time Mr Cameron has been to Washington since taking office two months ago.
Afterwards, they described the special relationship between their countries as essential to international security and prosperity.
Mr Cameron and Mr Obama said their talks addressed the future of Afganistan, the Gulf of Mexico oil disaster and BP's possible involvement with the release of the Libyan convicted of blowing up a US airliner over Lockerbie in Scotland in 1988 that killed 270 people.
Mr Cameron says Abdelbaset al-Megrahi should not have been given his freedom.
He also said said the decision to release al-Megrahi was taken by the Scottish Parliament, not BP.