Ukraine launched a big attack with at least 361 drones targeting Russia overnight, sparking a brief fire at the vast Kirishi oil refinery in Russia’s northwest, Russian officials said on Sunday, reporting no injuries.

As big powers talk about how to end the deadliest conflict in Europe since World War Two the drone war has escalated, with Russian drones downed in NATO-member Poland and attacks by Ukraine against oil refineries and pipelines in Russia, the world’s second biggest oil exporter.

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Russia’s defense ministry said at least 361 drones had been shot down by Russian air defense systems, including four guided aerial bombs and a US-made HIMARS missile. It did not give details about the location of the attacks.

Surgutneftegaz’s Kirishinefteorgsintez refinery, one of the top two refineries in Russia, was among the targets attacked by Ukrainian drones, Russian officials said.

Alexander Drozdenko, the governor of the Leningrad region, said that three drones were destroyed in the Kirishi area and that a fire sparked by falling debris had been put out. He said no one was injured.

Ukraine’s drone command confirmed it attacked the refinery and said it had “carried out a successful strike.”

Reuters was unable to immediately verify the scale of the damage, if any, to the refinery.

Kirishi refines about 17.7 million metric tons per year (355,000 barrels per day) of Russian crude, or 6.4 percent of the country’s total.

In recent weeks, the United States has stepped up pressure on NATO countries to tighten energy sanctions on Russia in a bid to curtail its revenues and help end the war with Ukraine — a conflict US President Donald Trump has struggled to bring to a close.

Trump said on Saturday that the US is prepared to impose fresh energy sanctions on Russia, but only if all NATO nations cease purchasing Russian oil and implement similar measures.

The EU is sticking to its deadline to phase out Russian oil and gas imports by 2028, it decided last week, despite pressure from the US to move more quickly.

Russia said on Sunday that it had fired a Zircon (Tsirkon) hypersonic cruise missile at a target in the Barents Sea and that Sukoi Su-34 supersonic fighter-bombers had carried out strikes as part of joint military exercises with Belarus.

An oil company in Russia’s Bashkortostan region will maintain production levels despite a drone attack on Saturday, regional governor Radiy Khabirov said.