Russian President Vladimir Putin, center, accompanied by Crimean leaders, Speaker of Crimean legislature Vladimir Konstantinov, left, Crimean Premier Sergei Aksyonov, right, and Sevastopol mayor Alexei Chalyi, back, enters the hall for a signing ceremony of a treaty for Crimea to join Russia in the Kremlin in Moscow, March 18, 2014. [Photo/icpress.cn]