The Kremlin says Russia's air force will press ahead with its operations in Syria and dismissed a US statement on the conflict there as unhelpful and clumsy.
US Secretary of State John Kerry has called on Moscow to ground its planes over Syrian battle zones, including over Aleppo.
But Kremlin spokesman Dmitry Peskov told a conference call with reporters on Thursday that the Russian air force would continue to support Syrian government troops and that what he called the "war on terror" would continue.
Mr Peskov urged Washington to deliver on a pledge to separate moderate Syrian opposition fighters from "terrorists" and called the latest US statement on Syria clumsy and unhelpful.
He was referring to a statement by US 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."
Despite growing US-Russia tensions, Mr Peskov said Russia remained interested in cooperating with the United States to try to resolve the Syria crisis.