You're reading: Reuters: Rebels down Ukraine helicopters, Putin denounces city assault

 Pro-Russian rebels shot down two Ukrainian helicopters on May 2, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. Though Ukrainian forces appeared to be carrying out one of their most concerted military operations yet, their advance on the ground was limited. Nevertheless, President Vladimir Putin's spokesman accused Kyiv of firing on civilians from the air in a "punitive operation" that destroyed an international peace plan.

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