Russian air defenses intercepted 660 Ukrainian drones in a major nighttime attack on 12 regions as well as the Russia-held Crimean peninsula, the Black Sea and the Azov Sea, Russia’s Defense Ministry said Friday.It appeared to be one of the biggest drone attacks on Russian regions and the illegally annexed Crimea since Russia’s full-scale invasion of Ukraine more than four years ago.

In an effort to turn the tables on Russia’s grinding war of attrition, Ukrainian long-range drones have for months been battering targets, including oil production and energy facilities, behind the front line and deep inside the country.The campaign has choked Russian fuel supplies and military deliveries, stalling its efforts on the battlefield, Western officials and analysts say, and heaped pressure on Russian President Vladimir Putin.Ukraine’s Security Service said it used drones to strike Russian navy ships and air defiance radars in Kerch, an important port city in Crimea.

The targets were two reconnaissance and mine-laying ships, the Volga and the Vyatka, and the cargo-passenger ferry Petropavlovsk, the agency said, claiming that the strikes started a large fire. The claim could not be independently verified.The major attack came hours after Ukrainian President Volodymyr Zelenskyy said on X that he had ordered “a 40-day influence operation,” believed to mean an escalation of attacks, aimed at “compelling [Russia] to end the war” after U.S. peace efforts over the past year yielded no breakthrough.

The successful strikes, including hitting targets in Moscow and St. Petersburg, have buoyed Ukraine.