Since the invasion of Crimea, President Vladimir Putin and President Barack Obama have had regular phone calls in an often half-hearted attempt to deescalate the ongoing crisis inside Ukraine. But as the U.S. and EU prepare to unveil new sanctions against Russia, Putin has decided the interactions should stop. The Kremlin has ended high-level contact with the Obama administration, according to diplomatic officials and sources close to the Russian leadership. The move signals an end to the diplomacy, for now. More