Russian forces are strengthening their positions and digging into the Kharkiv region in the north and along the southern front, the Institute for the Study of War states in its latest update.
This may be a sign that Russia is preparing for a major Ukrainian counterattack there and that the conflict may be protracted.
Russia is also approaching the city of Sevierodonetsk in Luhansk through attacks north, west and south of the city, according to the US-based think tank.