PARIS, France — The world diplomatic community was stunned today when U.S. President Barack Obama accepted Russian President Vladimir Putin’s challenge to a drinking contest.

The stakes: control of Ukraine, which Russian troops invaded several months ago.

The Paris talks between the U.S. and Russia have been ongoing since the invasion but have often been strained to the point of open hostility. But none of the assembled diplomats and journalists could have predicted a drinking contest between the two most powerful men in the world.