Russia launched a massive attack on Ukraine overnight into Saturday with hundreds of drones, killing at least one person, part of a stepped-up bombing campaign that has dashed hopes for a breakthrough in efforts to end the more than 3-year-old war.

A Russian drone attacked Sumy, damaging residential buildings and the power grid. A mother and son asked for medical assistance, according to the head of the Sumy regional military administration, Oleh Hryhorov.

Russia is open to peace with Ukraine but achieving its goals remains a priority, Kremlin spokesman Dmitry Peskov said Sunday, days after U.S. President Donald Trump gave Moscow a 50-day deadline to agree to a ceasefire or face tougher sanctions.