Ukrainian drones struck a major refinery deep inside Russia, military officials said Thursday, the fourth in three days in Kyiv’s monthslong campaign to choke Moscow’s vital oil sector.

Russia is one of the world’s biggest energy producers, with oil providing an economic mainstay as its army tries to push deeper into Ukraine in a slow and costly advance more than four years after Moscow launched its full-scale invasion.

The attacks have dented Russia’s refining capacity, bringing shortages at gas stations. Kyiv officials say the onslaught seeks to compel Russian President Vladimir Putin to seek a peace deal. There is no sign that strategy is working.

The refinery targeted is one of Russia’s biggest facilities

Ukraine’s General Staff said that its forces struck the Gazprom Neftekhim Salavat oil refining and petrochemical complex in Russia’s republic of Bashkortostan overnight, causing a fire at the facility.

The complex, located southeast of Moscow about 1,300 kilometers (800 miles) from Ukraine’s border, is one of Russia’s largest oil refining and petrochemical facilities, the General Staff said in a Telegram post.

The plant processes up to 74 million barrels of oil annually, producing gasoline, diesel fuel and other products, it said.

Russia’s Bashkortostan governor, Radiy Khabirov, said only that a drone attack wounded two civilians and started a fire in an industrial zone of Salavat.

Wildberries, Russia’s biggest online retailer whose giant warehouses have repeatedly been struck by Ukrainian drones, said a fire started at one of its facilities in the Salavat industrial zone after the overnight attack. The company said the facility was evacuated but that goods were not being stored there.

The attack came a day after Ukrainian anti-ship missiles and drones blitzed a major Russian naval base on the Black Sea coast.

Elsewhere, four explosive experts from Russia’s Emergency Ministry and a security guard were killed Thursday after an unspecified Ukrainian weapon exploded in Sevastopol, a port city in illegally annexed Crimea, the Russian-installed governor of Sevastopol Mikhail Razvozhayev said.

They were inspecting the site of a Ukrainian attack when “an enemy weapon detonated,” he said.

It was not possible to independently verify either side’s reports.

Russian official says another refinery’s repairs could take 6 months

Meanwhile, a Russian refinery in Orsk that was hit by Ukrainian drones earlier this week has suspended operations, Orenburg region Gov. Yevgeny Solntsev said Thursday.

He said that “key infrastructure, which cannot be restored at this time” was struck, including foreign equipment, and “taking (international) sanctions into account,” the repairs could take up to six months, Solntsev said in a rare public admission in Russia of the problems Ukrainian attacks are causing.

Ukraine’s General Staff had reported striking the Orsk refinery, in Russia’s Orenburg region near the border with Kazakhstan, on Tuesday.

Russian drone hits a Ukrainian passenger train, killing 2

Russia has responded by hammering Ukraine with ballistic missiles, jet-powered drones and glide bombs, all of which are powerful and hard to intercept. The strikes have killed more than 16,000 civilians since the war began, according to the United Nations.

Russian attacks featuring 133 long-range strike drones killed at least four people and wounded eight others across Ukraine overnight from Wednesday to Thursday, officials said.

A jet-powered Shahed drone struck a passenger train in the southern Odesa region, killing the engineer and his assistant, Ukraine’s state railway company, Ukrzaliznytsia, said Thursday.

A Russian drone killed two men on Wednesday evening in the southern city of Kherson, regional military administration chief Oleksandr Prokudin said.

Ukraine makes little headway on obtaining Patriot missiles

Ukraine desperately wants more U.S.-made Patriot interceptor missiles that can counter Russia’s ballistic missiles, but stocks of the air defense system reportedly are low because of the Iran war.

Ukraine so far this year has two and a half times fewer Patriot interceptors than in 2025, according to Ukrainian President Volodymyr Zelenskyy, saying he makes calls every day to try and source some more.

He said in an interview with CNN broadcast Wednesday evening, parts of which he posted on social media, that he is asking the United States to sell 5% of the interceptor missiles they have in stock to help Ukraine make it through next winter, when Russia’s strikes focus on the power grid.

He has so far obtained just 1%, he said.

In the first half of this year, European countries paid U.S. defense companies at least 3 billion euros ($3.5 billion) for military equipment they sent to Ukraine, according to a report Thursday by Germany’s Kiel Institute, which tracks assistance to Kyiv.

The Trump administration won’t provide its own aid to Ukraine but is allowing other countries to buy U.S. equipment that is sent on.

Military aid provided to Ukraine in the first half of 2026 was close to last year’s level, the Kiel Institute said, but financial and humanitarian aid was 41% lower than in 2025.