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.

The overnight attack was one of the largest on Ukraine and included strikes in the western part of the country, which is hit less often.