The warring sides remain far apart after the third round of U.S.-brokered peace negotiations on Wednesday. But there was progress on humanitarian issues.

Ukraine and Russia attacked targets on each other's territory on Thursday after brief direct talks between the two sides failed to make any progress on steps to end nearly three-and-a-half years of war.

The announcement appears to preclude any kind of top-level meeting or breakthrough ahead of the 50-day deadline for an agreement given by President Donald Trump.