Russia's Deputy Foreign Minister Sergei Ryabkov speaks during a news briefing in the main building of Foreign Ministry in Moscow, December 15, 2008. REUTERS/Denis Sinyakov

MOSCOW (Reuters) - 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.”

“We cannot interpret this as anything else apart from the current U.S. administration’s de facto support for terrorism,” Ryabkov was quoted as saying.

“These thinly disguised invitations to use terrorism as a weapon against Russia show the political depths the current U.S. administration has stooped to in its approach to the Middle East and specifically to Syria.”

U.S. officials said on Wednesday that Obama administration officials had begun considering tougher responses to the Russian-backed Syrian government assault on Aleppo, including military options, as rising tensions with Moscow diminish hopes for a diplomatic solution.

Ryabkov was quoted as saying that Moscow saw no alternative to an original U.S.-Russia plan to try to get a ceasefire in Syria and that Washington should focus on implementing it.

He said a seven-day ceasefire plan proposed by the United States was unacceptable however and that Moscow was proposing a 48-hour “humanitarian pause” in Aleppo instead.