Ukrainian long-range drones attacked an industrial plant around 1,300 kilometers (800 miles) inside Russia, local officials said Tuesday, while Ukraine’s army remained locked in an intense battle to hold back a Russian push on the key city of Pokrovsk in the eastern Donetsk region.

Unidentified drones were spotted over a Belgium military base housing U.S. nuclear weapons, sparking security concerns and an investigation into a potential spying operation.