The official, Alexander Venediktov, an aide to Security Council Secretary Nikolai Patrushev, also said Washington was supplying the Kurds with the most advanced weapons, according to RIA.
The United States is an international player in Syria's civil war. The U.S. backs the Syrian Democratic Forces (SDF), whose closest ally is the Kurdish YPG, who wants to oust Syrian President Assad, backed by Russia.
Washington also wants to contain Iran, for it sees the country's growing influence across the region as a threat to its closest Middle East allies Israel and Saudi Arabia.
On Wednesday, Israeli satellite images revealed Iranian military bases northeast of Syria's capital. Fox News published the images that reportedly showed two warehouses storing missiles capable of hitting all of Israel. According to the report, members of the Iran Revolutionary Guard's special operations Quds Force are operating the base.