Ukraine attacked Russian oil fields with dozens of drones while attempting a land incursion through proxies on Tuesday. Russia said it killed 234 fighters in response.

The Russian Defense Ministry blamed the Kyiv regime and Ukraine’s terrorist formations that were firm on Russian forces unable to eliminate the attack.

“Moscow’s military and security forces killed 234 fighters while thwarting the incursion,” the Ministry said.

Ukraine-based armed groups had launched cross-border raids in the western Belgorod and Kursk regions of Russia.

The Russian Defense Ministry pointed out that Ukrainian armed groups were equipped with tanks and armored combat vehicles to annex Russian land.

The Russians refused to accept that those attackers were Russian puppets mimicking an attack; however, the border was under attack.

Russia and Ukraine have both used drones to strike critical infrastructure, military installations, and troop concentrations in their more than two-year war, with Kyiv hitting Russian refineries and energy facilities in recent months.

Russia said Ukrainian proxies had sought to cross the Russian border in at least seven attacks that Russian forces had repelled.

The Russian-speaking Ukrainian proxies said they had breached the border, a claim denied by Russia.

In one of the biggest Ukrainian drone attacks on Russia to date, Moscow said it downed 25 Ukrainian drones over regions including Moscow, Leningrad, Belgorod, Kursk, Bryansk, Tula, and Oryol. Waves of drone attacks continued through the day, the defence ministry said.

Russian officials reported attacks on energy facilities, including a fire at Lukoil’s, opens new tab NORSI refinery and a drone destroyed on the outskirts of the town of Kirishi, home to Russia’s second-largest oil refinery.

Gleb Nikitin, governor of the Nizhny Novgorod region, said emergency services were working to put out a blaze at the NORSI refinery.

“A fuel and energy complex facility was attacked by unmanned aerial vehicles,” Nikitin said on Telegram.

Industry sources told Reuters on condition of anonymity that the main crude distillation unit (AVT-6) at NORSI was damaged in the attack, which means that at least half of the refinery’s production is halted. Lukoil declined to comment.

According to industry sources, NORSI refines about 15.8 million tonnes of Russian crude a year, or 5.8% of total refined crude.

It also refines about 4.9 million tonnes of gasoline, 11% of Russia’s total, 6.4% of diesel fuel, 5.6% of fuel oil, and 7.4% of the country’s aviation fuel, according to industry sources.

Striking Russian oil facilities is a problem for President Vladimir Putin as he faces off against the West over Ukraine, with domestic gasoline prices sensitive ahead of a March 15-17 presidential election.

Russia imposed a six-month ban on gasoline exports on March 1.

Along with Iran, Saudi Arabia and the U.S., Russia has vast energy reserves but has, since oil was discovered in the wilds of Western Siberia in the 1960s, often relied on Western technology to exploit and refine its crude.

The Kremlin said the Russian military was doing everything necessary and that what it calls its military operation in Ukraine would continue.

Russia says it has destroyed more than 15,000 Ukrainian-launched drones since the start of the war.