European leaders reacted to the suspension of Russian gas supplies to Poland and Bulgaria with a mixture of defiance and concern on Wednesday, as the Kremlin threatened to turn off flows to more countries. EU Commission President Ursula von der Leyen called the cuts “unjustified and unacceptable” and said it was “yet another attempt by Russia to use gas as an instrument of blackmail” over the conflict in Ukraine. “We are prepared for this scenario,” she said, adding that contingency plans have been put in place and that the EU response would be “immediate, united and coordinated.” The EU was n…