Ukraine struck oil facilities deep inside Russia in overnight attacks, President Volodymyr Zelenskyy said Thursday, as Kyiv stepped up efforts to weaken Moscow's wartime economy.

The repeated strikes have caused fuel shortages and rattled Russians while heartening Ukrainians who are enduring regular Russian barrages that Kyiv's weakened air defenses are struggling to counter.

Ukrainian forces hit a refinery in Bashkortostan, more than 1,300 kilometers (800 miles) behind the front line in eastern Ukraine, as well as a refinery in the Yaroslavl region, almost 700 kilometers (400 miles) from the Ukrainian border, Zelenskyy said on social media.

Also, Ukrainian forces hit two Russian military patrol boats in the Black Sea, according to Zelenskyy, as well as vessels belonging to Moscow’s so-called shadow fleet, which Russia uses to evade Western restrictions on its oil exports. He did not provide details about the vessels or the extent of the damage.

The Russian Defense Ministry said Thursday that its air defenses overnight shot down 605 Ukrainian drones over several Russian regions, as well as illegally annexed Crimea and the Black and Azov seas.