Ukraine launched a major nighttime drone assault on Russia, hitting a dozen Russian regions, Russian-held Crimea and the surrounding seas, in what Moscow described as one of Kyiv’s biggest drone attacks since Russia’s full-scale invasion more than four years ago.

Russia’s Defense Ministry said its air defenses intercepted 660 Ukrainian drones. It cited May 17 as the previous biggest attack of the past year, when 556 drones were reportedly used. The attack was part of a broader effort by Ukraine to use long-range drones to pressure Russia by striking oil production and energy facilities behind the front line and deeper inside Russia, according to Western officials and analysts. They said this is aimed at disrupting fuel supplies and military deliveries and raising pressure on President Vladimir Putin.

Initial Russian reports on damage were limited, and Moscow typically does not specify targets or detailed results of Ukrainian drone attacks. An independent outlet, Astra, reported a chemical plant and a hydroelectric plant in Novomoskovsk were attacked and caught fire, but the Associated Press could not independently verify the claims.

Moscow Mayor Sergei Sobyanin said 47 drones were downed as they flew toward the Russian capital, without reporting casualties or damage. Ukraine’s Security Service said it used drones to strike Russian navy ships and air defense radars in Kerch, Crimea. It claimed attacks hit the Volga and Vyatka reconnaissance and minelaying ships, as well as the cargo-passenger ferry Petropavlovsk, starting a large fire—claims that also were not independently verified.

Hours before the strike, Ukrainian President Volodymyr Zelenskyy said he had ordered a “40-day influence operation,” which was widely understood as an escalation intended to compel Russia to end the war. He said promises of foreign support he received at a recent G7 summit, including from U.S. President Donald Trump, would help Ukraine increase pressure. The report also noted that Russia and Ukraine continued exchanging prisoners of war, with 160 returning from each side on Friday.

In parallel, Ukraine reported ongoing Russian attacks, including strikes that killed civilians and wounded dozens in areas such as Kharkiv and across multiple regions. Ukraine also said its defenses stopped 174 of 189 Russian drones overnight, though it reported that four of seven Iskander-M ballistic missiles reached targets.