The U.S. Department of Defense said there was a 24-hour period with "little activity" and no observed shelling in Ukraine, according to an update posted Thursday evening in Washington.
There were subsequent, unconfirmed reports of explosions Friday morning in Lviv, a city in Western Ukraine near the Polish border. Military reports on the ground remain difficult to confirm as the situation is fluid.
Ukrainian officials have said Russian attacks across Ukraine have resulted in numerous civilian deaths over the past day.
There are reportedly survivors in the rubble of a bombed theater in the besieged city of Mariupol, it emerged on Thursday. More than a thousand civilians were said to be sheltering in the building.
Meanwhile, Ukrainian President Volodymyr Zelenskyy delivered a scathing address to German lawmakers on Thursday morning, urging Germany to do more to help Ukraine.