Several Ukrainian drones targeted Russia's largest refinery, causing extensive damage to the distillation facility and leading to the country banning exports of diesel. 

Russia had no air defense against the drones in Omsk, a city deep in Siberia, because Russia had assumed the area to be too remote to be targeted. The strike has further deepened Russia's fuel crisis. 

Until Monday's strike in Siberia, Ukrainian attacks on Russia's oil infrastructure were limited to within 1,000 miles of Kyiv-controlled territory, the Wall Street Journal reported. 

The strike in Siberia lies nearly 1,500 miles away, and the drones that hit the facility had to take a longer route to avoid air defenses. According to the drones' manufacturer, Fire Point, the drones have a range of 2,100 miles.