Russian President Vladimir Putin (right) and British Prime Minister David Cameron met earlier this month. Cameron said then that he was encouraged by Russia's willingness to take part in a peace conference on Syria. Now, Russia is said to be angry about the EU's decision to lift an embargo on arming the Syrian opposition. Alexey Nikoksky /AFP/Getty Images hide caption

itoggle caption Alexey Nikoksky /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

Carla del Ponte, a diplomat and prosecutor who now serves on the Independent International Commission of Inquiry for Syria. Salvatore Di Nolfi /EPA /LANDOV hide caption

itoggle caption Salvatore Di Nolfi /EPA /LANDOV

Opposition fighters from the Free Syrian Army last month in Aleppo, Syria. Maysun/EPA /LANDOV hide caption

itoggle caption Maysun/EPA /LANDOV