Heavy security as U.S. Deputy Secretary of State William Burns arrives in Tripoli ... one week after a deadly attack on the U.S. consulate in the eastern Libyan city of Benghazi.
Burns will meet with Libya's new leaders and is scheduled to attend a ceremony for U.S. ambassador to Libya Christopher Stevens, who was killed in the attack.
The government has already offered its apologies.
Stevens and three other Americans died last week when gunmen attacked the U.S. consulate.
U.S. government sources now say that the consulate sent a message that it was suddenly under heavily armed assault at 9:35 in the evening ... contradicting earlier claims that the building was attacked by crowds of protesters upset over a video mocking the Prophet Mohammad.
A top U.S. counter-terrorism official told Congress Wednesday the assault was a "terrorist attack" that may have had an al Qaeda connection.
