The US defence officials said on Thursday that the Russian airstrikes in Syria were not targetting Islamic State (IS) targets as Moscow had claimed.
"The Russians were very clear publicly that they were going to strike ISIL," said Steve Warren, spokesman for the US-led counter-IS military campaign Operation Inherent Resolve. "I'm not going to get into exactly who they hit, but we don't believe that they struck ISIL targets."
ISIL was another acronym for the extremist group now controlling a vast areas of lands in Iraq and Syria, Xinhua news agency reported.
"(In the place) where they (Russians) struck yesterday, we don't believe there was any ISIL there," Warren added.
Moscow began airstrikes in Syria on Wednesday after weeks of military build-up around Syria's coastal province of Latakia.
On Thursday, Russian Foreign Minister Sergey Lavrov strongly defended Moscow's bombing campaign in Syria, saying it is targeting terrorist groups and not aimed at keeping President Bashar al-Assad in power.
"We see eye to eye with" the US-led coalition on targeting ISIL, al-Nusra and other terrorist groups, Lavrov said at the United Nations headquarters. "We have the same approach."