US Ambassador to NATO: Russian army has been in Ukraine since April 2014

Russia's direct intervention took place last August.

It was said by US Ambassador to NATO Douglas Lute, the Ukrainian service of the RFE/RL reports.

Russian military specialists perform a command and control role in the conflict and operate advanced military equipment, he said before a meeting of NATO defence ministers in Brussels.

Russian troops in Ukraine are represented by intelligence operatives and soldiers in and out of uniform, Lute said.

The US Ambassador to NATO noted that Russia's direct intervention took place in August, when Russia sent battalions to Ukraine.

The US doesn't see another such direct intervention (by Russian units) as imminent, Lute said.