Washington: The Pentagon called Russia's airstrikes "contradictory" to their position of fighting extremism in Syria despite Moscow's insistence that the air raids were against the Islamic State (IS) targets, Xinhua reported.
"I want to be careful about confirming information, but it does appear that they (Russian airstrikes) were in areas where there probably were not IS forces," said Defence Secretary Ash Carter, referring to another acronym for the IS.
Russia began airstrikes in Syria on Wednesday after weeks of military buildup inside the Arab country which was scrambling to deal with a civil war and insurgency of the IS.
Russian Defence Ministry said its air forces carried out 20 sorties during the first round of air strikes against the IS in Syria, hitting eight targets, including a command centre.
Eight facilities held by the extremist group had been hit, with a command post and militant control centres in the mountainous areas of Syria being completely destroyed, according to the ministry.
Earlier on the day, Russian Defence Ministry spokesman Igor Konashenkov said Russia's military operations targeted only IS targets.
"Strikes would be carried out against the military equipment, communication centres, transport vehicles, arms depots, ammunition as well as fuels and lubricant materials of IS terrorists," Russia' s Interfax news agency cited Konashenkov as saying.