By David Lawder and Andrea Shalal WASHINGTON (Reuters) -Punishing sanctions imposed by the United States and its allies on Moscow for invading Ukraine are pushing Russia into recession and starting to turn it back into a closed economy, a senior U.S. Treasury official said on Friday. The official, speaking on condition of anonymity, told reporters that the Treasury sees Russia as struggling with steep inflation, diminished exports and shortages despite a recovery of its rouble against the dollar. The official dismissed the rebound as driven by stringent capital controls and foreign exchange cu…