After more than a decade in power, Russian President Vladimir Putin is facing what may be his most turbulent and difficult year in office. His economy is crumbling under the global collapse in gas prices; US and European economic sanctions are punishing his inner circle and most powerful state institutions; his military is occupying Crimea and still fighting in eastern Ukraine. Just before New Year's, thousands gathered in Moscow to protest the politically tinged conviction of opposition leader Alexei Navalny, who announced from the courthouse, "This regime has no right to exist." Putin's rule has been secure since he took...