Russia launched its largest aerial assault of its three-year war on Ukraine overnight, targeting the capital and other regions with missiles and drones for a second night in a row, even as the two sides prepared to conclude a major prisoner exchange.

Fourteen people were reported killed in Ukraine, with its air force saying 22 locations were hit by Russian air strikes.

The massive missile and drone attack across Ukraine followed large strikes the night before, and casts more doubt on the U.S.-brokered peace process.