The Kremlin has said that Moscow and Washington have been exchanging information about a planned cease-fire in Syria that is due to come into effect on February 27.
But Russia's Foreign Ministry on February 25 accused some officials in Washington of trying to sabotage the cease-fire deal by speaking of an alternative "Plan B" if Moscow and Damascus fail to take serious steps toward negotiating a political transition in Syria.
U.S. Secretary of State John Kerry made the remarks about a "Plan B" in testimony to the U.S. Senate Foreign Relations Committee on February 23.
He said "the proof" of the sincerity of Moscow and Damascus would "be in the actions that come in the next few days."
Staffan de Mistura, the UN's Syria envoy, says he will announce on February 26 the dates for a new round of talks between Syria's warning parties.
Neither the Islamic State militant group nor the Al-Qaeda-linked Al-Nusra Front are parties to the cease-fire deal, and neither will be involved in the upcoming peace talks.