President Obama and British Prime Minister David Cameron in the Oval Office of the White House on Monday. Jim Watson /AFP/Getty Images hide caption

itoggle caption Jim Watson /AFP/Getty Images

British Prime Minister David Cameron (left) and Russian President Vladimir Putin viewed the Sochi Olympic Park along the Black Sea coast by helicopter Friday. Nikolsky Alexei /ITAR-TASS /Landov hide caption

itoggle caption Nikolsky Alexei /ITAR-TASS /Landov

A rebel fighter raises his weapon after firing a missile Sunday toward Syrian government troops in the northern city of Aleppo. Syria's largest city has been the scene of heavy fighting for the past three months. Both sides control part of the city, and the fight has been a stalemate recently. Narciso Contreras/AP hide caption

itoggle caption Narciso Contreras/AP