A drone attack overnight on Jan. 14 caused damage to an industrial facility in the city of Engels, located in Russia's Saratov region. Engels lies around 600 kilometers (370 miles) from the front lines in Ukraine.

Ukraine continues to cripple Russia's energy sector by hitting numerous oil refineries, depots, chemical plants, and more with drones.

Ukraine launched waves of long-range strikes, including its ATACMS and Storm Shadow missiles, at targets inside Russia.

Kyiv targeted Russian factories developing weapons, an oil depot, a refinery and air defense systems, a Ukrainian official said.

While the ground war in eastern Ukraine has settled into a grinding war of attrition, where Russian forces sacrifice hundreds, sometimes thousands, of troops a day, for small, incremental advances, the air war has the two sides inflicting significant losses on each other's energy sector.

Located in Saratov Oblast, over 750 kilometers from the Ukrainian border, Engels airbase is home to Russian heavy bombers.

Roman Busargin, Saratov regional governor ... while Ukraine will likely plug away with further efforts to damage Russia's oil facilities deep into Russian territory.

The barrage appeared to be one of the largest recent assaults in Ukraine’s campaign to damage Russia’s war machine on its home territory.

Europe warns its airlines to stay away through next summer, as Ukraine turns skies of western Russia into a battlefield.

Ukraine's latest aerial bombardment was spread across 12 Russian regions, with targets including an oil depot and an airfield in Engels.

KYIV, Ukraine -- The Ukrainian military said Wednesday that it struck a fuel storage depot deep inside Russia, causing a huge blaze at the facility that supplies an important Russian air base. Russian officials acknowledged a major drone attack in the area, and said that authorities had set up an emergency command center to fight the fire.