Moscow ? Russia cut off all gas supplies to Europe through Ukraine on Wednesday, playing hardball in a weeklong standoff that has left more than a dozen countries struggling to cope with dwindling energy supplies in the depths of winter.

The U.S. put the blame squarely on Russia, accusing Moscow of using its energy resources to threaten its neighbors.

But Prime Minister Vladimir Putin endorsed the move, even as factories shut down in eastern Europe, schools closed and tens of thousands of people scrambled to find other ways of keeping warm.

Insisting that Ukraine was responsible for the crisis, Putin appeared determined to force Kiev to back down and accept increased prices for natural gas. The two sides were to meet today in the first face-to-face talks since negotiations broke down on New Year’s Eve.