The Russian Defense Ministry said Wednesday that Ukrainian troops should surrender to save themselves in Pokrovsk, a transport and supply hub seen as a gateway to bigger nearby cities.

Western analysts say the attacks on energy infrastructure so far have had a serious — but not crippling — effect. Ukrainian drones have repeatedly hit 16 major Russian refineries, representing about 38% of the country’s nominal refining capacity, according to a recent review by the Carnegie Endowment, a U.S.-based think tank.