Special Representative of the U.S. State Department for Ukraine Negotiations Kurt Volker says that he personally made sure that military actions in the east of Ukraine were a consequence of Russian intervention.

"As I saw on my recent trip, there is a hot war in eastern Ukraine that has created a grinding, degrading humanitarian crisis all caused by Russia's intervention," he wrote on Twitter on Tuesday.

Volker also said that the U.S. continues to support a UN-mandated peacekeeping force to facilitate implementation of Minsk agreements, "but Russia's proposal for an OSCE "protection force" is a non-starter," he added.

Volker thanked Danish Embassy to the U.S. for hosting a discussion on countering Russian aggression in eastern Ukraine, and attached photos from the event.