Russia is outraged by the threatening tone of the latest U.S. statement on Syria viewing it as tantamount to supporting terrorism, Russian Deputy Foreign Minister Sergei Ryabkov said on Thursday according to Russian news agencies.

Ryabkov was referring to a statement made by U.S. State Department spokesman John Kirby who said on Wednesday that Russia had an interest in stopping the violence in Syria because extremists could exploit the vacuum there and launch attacks "against Russian interests, perhaps even Russian cities."

Ryabkov was quoted as saying the statement was "an emotional outburst."

He also said a seven-day ceasefire plan proposed for Syria by the United States was unacceptable for Russia and that Moscow was proposing a 48-hour "humanitarian pause" in the city of Aleppo instead.