Ukrainian drones struck Russia's Bolkhov semiconductor plant in Oryol Oblast, which is producing parts for Sukhoi warplanes and Iskander and Kinzhal missiles, the General Staff of Ukraine's Armed Forces said on May 21.
The statement comes after Russia claimed to have downed over 150 Ukrainain drones overnight in multiple regions, including 53 in Oryol Oblast.
The region's governor, Andrey Klychkov, initially reported no damage or casualties, but later said that the semiconductor plant and several residential buildings were damaged.
Ukrainian Telegram channel Supernova+ shared what it claimed to be footage of the burning and damaged facility.
Ten drones hit the plant's premises, resulting in a fire, the General Staff reported. The full consequences of the attack are being determined.
The plant has been sanctioned by the U.S. since last year over its role in the Russian military-industrial complex.
The Bolkhov plant is one of Russia's leading producers of semiconductor devices and components, focusing on diodes, microcircuits, optoelectronic switches, and more, the General Staff said.
The factory supplies at least 19 Russian plants involved in the production of Sukhoi planes or Iskander and Kinzhal ballistic missiles. Despite the sanctions, it produces almost 3 million devices per year, according to the Ukrainian military.
Explosions were also reported in the Tula and Ryazan oblasts, while Ukrainain official Andrii Kovalenko claimed that facilities of the Russian military-industrial complex were attacked by "unknown drones" in Oryol Oblast.
Temporary flight restrictions were introduced at the Yaroslavl, Kostroma, and Kaluga airports.
Ukraine regularly launches drone attacks against Russian military and industrial facilities in the rear to undermine Moscow's ability to wage its all-out war.