KYIV, Ukraine (AP) — Ukraine kept up its heavy drone assault on Russia, setting fire to a major oil refinery in the south, as President Vladimir Putin acknowledged for the first time on Sunday that the country was facing a “certain deficit” of fuel and vowed to strengthen protection of oil facilities and boost fuel output.

Ukraine has markedly stepped up its long-range attacks on Russian military industries and energy facilities in recent months, aiming to cut Moscow’s revenue for its invasion — now in its fifth year — and make Russians feel the consequences.