Russia has built up its air defense systems to the highest levels since August of last year, State Department spokeswoman Marie Harf said in a statement. Russia has been supporting separatists battling Kyiv forces, Censor.NET reports citing Fox News.
Harf said Russia now has deployed more troops and military material on its border with Ukraine than at any time since the heaviest fighting in October.
"After maintaining a relatively steady presence along the border, Russia is sending additional units there," Harf said. "These forces will give Russia its largest presence on the border since October 2014."
Despite Moscow's denials of any involvement in the escalating tensions, Harf said Russians and separatists are conducting complex training missions that leave "no doubt" that Russian troops are present in that part of the embattled country.
The cease-fire agreement, which sought to end the months of fighting between the Ukrainian government and the separatists, is being violated, Harf said.