Twenty years ago the Russian president Boris Yeltsin appointed his fourth prime minister in less than 18 months: Vladimir Putin, then a relatively unknown security services chief with scant experience of politics. Few could have predicted that two decades later Putin would still be ruling Russia, having taken on a dominant role in world affairs. But the anniversary comes at a time of uncertainty in the leader’s reign. Putin’s approval ratings remain at a level most western leaders would envy, but they have taken a hit from a stalling economy and declining living standards