Vladimir Putin's return to the Russian presidency amid mass protests in 2012 ushered in a ruthless crackdown on dissent. 'They ruined my big day, now I'm going to ruin their lives, ' Putin was alleged to have threatened after demonstrators clashed with police on the eve of his inauguration for a controversial third term. Now Boris Nemtsov is dead, other key opposition leaders are either in prison or under house arrest and the Kremlin is using the war in Ukraine to further its domestic aims, encouraging the rise of violent pro-Putin groups and labeling protesters 'national traitors'....