Ukrainian drones hit more Russian oil facilities and set two oil tankers ablaze in the Sea of Azov on Thursday, a day after U.S. President Donald Trump pledged to grant Kyiv a license to manufacture the Patriot air defense systems to protect its cities.

A top Ukrainian official, meanwhile, cautioned that it could take a year or more for the country to produce Patriot interceptor missiles.

The Kremlin said the license deal reflected what it called Washington’s “ambivalence” but noted it appreciated Trump’s efforts to help broker a peace deal to end the war, which Russia launched over four years ago.

Ukraine’s drone strikes on oil refineries and other infrastructure across Russia has triggered a widespread fuel crisis with gasoline shortages and rationing in multiple regions and motorists waiting for hours to fill their tanks. Moscow has responded by intensifying its bombardment on Kyiv and other cities, exposing Ukraine’s vulnerability to ballistic missile strikes.

Ukrainian President Volodymyr Zelenskyy described the latest strikes on Russia’s infrastructure as part of Kyiv’s campaign of “long-range sanctions” carried out in response to Moscow’s refusal to halt the fighting.

“We have long proposed that Russia end this war, and every day of delay should bring the feeling of war to where it all began — to Russia,” Zelenskyy said.

A Ukrainian drone strike triggered a fire at an oil depot in the western Russian city of Tver, according to acting Gov. Vitaly Korolyov.

Oil reservoirs also were set ablaze by drones in Vyazniki, in the southern Stavropol region, said Gov. Vladimir Vladimirov, forcing the evacuation of several apartment buildings near the facility.

In the Sea of Azov, Ukrainian drones set two oil tankers on fire, according to Rostov Gov. Yuri Slusar, who said one of the ships was still burning and its crew evacuated.

-AP