U.S. Secretary of Defense Leon Panetta was in Libya, the first Pentagon chief to visit the country.
Panetta's visit comes after rebels in an eight-month campaign earlier this year ousted Muammar Qaddafi after 42 years of rule.
Panetta met with the Libyan prime minister and the defense minister.
At a news conference with Prime Minister Abd al-Raheem al-Keeb, Panetta called on the new transitional government to unite all of Libya's disparate groups and said the United States would provide whatever assistance the Libyans needed.
Panetta's visit came after the United Nations, the United States, and Britain announced on December 16 they were lifting sanctions on Libya's central bank and the Libyan foreign investment bank and unfreezing billions dollars.
The Libyan banks' assets abroad were frozen as rebels earlier this year mounted their campaign to end Qaddafi's rule.