Russia unleashed its largest overnight drone attack of the war on Monday, launching cruise and ballistic missiles in a barrage that lasted all night and struck locations across Ukraine, even as Kyiv and Moscow began a days-long prisoner exchange involving hundreds of soldiers.

The attack used almost 500 drones and missiles, breaking a record set just days earlier, as Russia tries to overwhelm Ukraine’s air defenses, which shot down most of the weapons.

Russia launched 499 drones and ballistic and cruise missiles against seven provinces across Ukraine, of which the Ukrainian Air Force claimed to have downed all but 22.