U.S. President Barack Obama and British Prime Minister David Cameron (L) appear during a joint press conference in the East Room of the White House in Washington

U.S. President Barack Obama (R) and British Prime Minister David Cameron meet in the Oval Office of the White House in Washington

Britain's Prime Minister David Cameron (C) tours 1776 as he attends a cyber breakfast in Washington

British Prime Minister David Cameron tours 1776 as he attends a cyber breakfast in Washington