As reported by Censor.NET citing UNIAN, it was declared by NATO Secretary-General Jens Stoltenberg.
"Regarding the Russian presence in eastern Ukraine, we have stated again and again that Russia is present with military personnel. And it is based on our own intelligence sources, it's based on open sources, it's based on reports in the media, it's based on reports from non-governmental organizations… But today that's also confirmed by President Putin. He stated that Russia has personnel in eastern Ukraine, and that this personnel - they have conducted military activities, and that's what we normally call soldiers," Stoltenberg said.
NATO Secretary-General called on Russia to comply with the Minsk agreements: withdraw heavy weapons, withdraw forces, ensure the cease-fire. Full implementation of the Minsk agreements is the only way to a peaceful negotiated solution to the crisis in eastern Ukraine, he stressed.
As previously reported, at the annual press conference in Moscow on Dec. 17, Russian President Vladimir Putin admitted the presence of Russian military in eastern Ukraine, who he said were not regular troops.