Small groups of Russian troops have pierced parts of Ukraine’s defenses in its eastern Donetsk region, according to local officials and monitoring groups, adding to Kyiv’s complications as Russia attempts to encircle the key strategic city of Pokrovsk.

Russian forces have made a sudden thrust into eastern Ukraine near the coal mining town of Dobropillia, a move that may be designed to increase the pressure on Kyiv to cede land as the U.S. and Russian presidents prepare to meet.