KYIV, Ukraine (AP) — Russia launched its biggest aerial attack against Ukraine overnight, a Ukrainian official said Sunday, part of an escalating bombing campaign that has further dashed hopes for a breakthrough in efforts to end the 3-year-old war.

Moscow has been escalating its bombardment of Ukraine over the past several months as U.S.-mediated peace talks stall.

Russia launched 537 drones and missiles into Ukraine overnight into Sunday morning, according to Ukraine's air force, with a Ukrainian F-16 fighter jet and its pilot also reported lost during efforts to repel the attack.