The Ukrainian armed forces have deployed a new kind of drone to defend their country, one filled with a pyrotechnic thermite mixture that rains fire down on enemy positions. Its use is highly controversial.

A Ukrainian drone attack launched overnight succeeded in destroying an ammunition depot in the western Russian region of Tver, a source from Ukraine’s Security Service (SBU) told CNN on Wednesday.

Management at the Russian-held Zaporizhzhia nuclear power plant in eastern Ukraine accused Ukrainian forces on Friday of launching a drone attack on a nearby electricity substation and posing a threat to the plant.