Ukrainian drone forces have struck Russia’s energy infrastructure again, targeting Rosneft’s Ryazan refinery—one of the nation’s largest crude processing facilities. The attack caused explosions, fires, and thick smoke at the plant, which processes more than 260,000 barrels of crude per day, accounting for about 5% of Russia’s total refining capacity.

Earlier on the same day, Ukrainian forces also hit an oil depot in Russia-occupied Luhansk, continuing a series of operations aimed at key energy sites. Rosneft’s facilities have been repeatedly targeted this year, including an August strike that forced temporary shutdowns.

Other Russian refineries have also been affected. In August, the Saratov refinery in the Volga region, which processes 140,000 barrels daily, had to pause operations following a drone attack. A Lukoil refinery in Volgograd, Russia’s second-largest plant and an important fuel supplier to the southern federal district, was also damaged by drone strikes in mid-August.

Over the past month, at least six refineries and the fuel and gas processing complex at the Ust-Luga Baltic port suffered varying levels of damage from Ukrainian drone operations. Some heavily damaged units may require up to six months for repairs.

Analysts expect Russia to increase crude oil exports in the coming weeks to offset the impact of reduced domestic refining capacity.