Russia and Ukraine struck each other’s energy infrastructure, hitting oil facilities in a key Russian Black Sea port as well as gas and oil assets in two Ukrainian regions.

While Ukraine’s attacks signaled the latest attempt to “bring the war home to Russia” and potentially crimp its foe’s oil revenues, the US Embassy in Kyiv warned Saturday that a “potentially significant air attack” on Ukraine may be imminent.

Ukraine’s Special Operation Forces, working jointly with the Security and Defense Forces, targeted the Sheskharis oil terminal, the largest on Russia’s Black Sea coast, and the Grushovaya storage facility that supplies oil to the terminal, the military authority said in a Telegram statement.

Kyiv also claimed an attack on a major chemicals petrochemicals facility deep into Russian territory. Ukrainian state energy company Naftogaz said its oil and gas facilities in the country’s east have been targeted by Russian strikes for more than 24 hours, causing serious damage.

Russia’s oil-pipeline operator Transneft PJSC, which owns Sheskharis and Grushovaya on the Black Sea coast, didn’t respond to a request for comment.

Previous attacks on Sheskharis in early April temporarily halted loadings there. Last month, the terminal shipped more than 544,000 barrels of Russian crude oil per day, according to Bloomberg terminal data.

Satellite images from NASA’s Fire Information for Resource Management System taken on Saturday show a relatively fresh heat anomaly at the Grushovaya depot, stretching up in the mountains in the vicinity of the port. A detected heat anomaly could signal a blaze.

A NASA FIRMS image taken on Saturday signals fire at the Grushovaya terminal that ships oil toward NovorossiyskSource: Bloomberg

Russia’s regional emergency services said falling drone debris caused a fire at an oil depot in Novorossiysk, Debris also fell on the local oil terminal, the authorities said, without providing further details. The overnight drone attack injured two people and damaged a residential building in the port city, they said.

Russia’s Defense Ministry said Saturday its forces had downed 800 Ukrainian drones over the past 24 hours.

The US Embassy said its warning of a potential air attack “over the next 24 hours” applied to all of Ukraine. The statement on its website didn’t provide further details.

Ukraine has been ramping up drone strikes on its foe’s oil assets, from refineries to the national crude-pipeline network. The attacks reduce Russia’s ability to ship, process crude and benefit from the global oil rally driven by the war in the Middle East.

Strikes this month have partly or completely halted operations at several key refineries in central Russia, the nation’s largest fuel-consuming area, cutting the total oil-processing volumes in the country to multi-year lows and raising concerns of fuel shortages at the start of the high-demand summer season.

The Kremlin sees no risk of any fuel supply disruptions, spokesman Dmitry Peskov told reporters this week.

Chemical Plant

In a separate statement on Saturday, Ukrainian President Volodymyr Zelenskyy said the nation’s Security Service struck the Metafrax Chemicals facility in Russia’s Perm region, some 1,500 kilometers (over 930 miles) from Moscow. The plant’s operations were halted after the attack, Zelenskyy said.

Metafrax is one of Russia’s largest producers of methanol, a key raw material for plastics, resins, and adhesives. The company hasn’t commented on the incident.

Read more: Ukraine’s Drones Now Strike 1,000 Miles Inside Russia

Perm region Governor Dmitry Makhonin said on Telegram that drones had targeted an unspecified industrial enterprise in the region overnight, and that emergency conditions had later been lifted.

Ukraine attacked long-range targets deep within Russia, including in the Perm region, over the past few weeks.

Ukraine attacked long-range targets deep within Russia, including in the Perm region, over the past few weeks.

Luhansk Strike

Separately, the number of victims of a drone strike on Starobilsk in the Russia-occupied Luhansk region of Ukraine grew to 18, Tass reported, citing emergency services as more victims were pulled from the rubble of what Russian authorities said was a college dormitory.

Ukraine denied targeting civilian facilities and said it had struck the headquarters of a special Russian drone unit.

Read more: Putin Vows Response After Saying Six Died in College Strike

Also on Saturday, Latvian authorities said they were investigating a drone crash and explosion in a lake near the country’s border with Belarus on Saturday. No injuries were reported and the origin of the drone hasn’t been identified.

On Friday, Estonia’s foreign minister accused Russia of “guiding” stray Ukrainian military drones toward NATO countries after a series of airspace incursions in the Baltic states this week.