Russia directly impacts on the decisions of illegal armed formation in the east of Ukraine, U.S. Ambassador to NATO Douglas Lute said.

"Russia continues to wield significant influence among the separatists in Donbas. Although the presence of regular Russian troops has decreased – who were responsible operating some of the heavy weapons that have been withdrawn – the drop in fighting wouldn't have been possible if it were up to the separatists alone," he sais at a press conference in Brussels.