Cameron arrived in the U.S. on Monday. He is visiting the White House for talks with Obama on subjects ranging from Syria's civil war to preparations for a coming summit of the world's leading industrial nations in Northern Ireland.
The prime minister also is due to receive a briefing with the director of the FBI in Washington on the response to terrorism in the U.S. before flying to Boston, where he will discuss how U.S. authorities responded to the Boston Marathon attacks exactly four weeks ago.
In Boston, Cameron will visit the statehouse and meet with Gov. Deval Patrick to extend his condolences and discuss lessons that can be learned from the attacks, which killed three people and injured more than 260 others.
"'I look forward to going there to pay tribute to the people of that remarkable city," Cameron told a press conference in Washington.