"In Horlivka, a fresh formation of Russian troops (up to 300 men) has taken control of the city,” Tymchuk wrote.
“The soldiers arriving were dressed in new camouflage uniforms, unmarked, well-equipped and well-armed."
Since the arrival of the Russians in the town, the number of local fighters has fallen sharply, said the expert.
Elsewhere, in Volnovakha district, Russian-backed militant units have again moved up to the frontline positions of the Ukrainian armed forces, Tymchuk said.
"Two fresh formations of the enemy, together numbering up to 200 people, were observed, along with six armored vehicles. Active intelligence gathering is also observed in the area (flights of UAVs and sabotage and reconnaissance groups of the enemy)," Tymchuk said.