A small number of US special operations forces will be deployed to northern Syria to work with local ground forces in the fight against Islamic State jihadists, Interfax news agency reported.
The deployment marks the first time US troops will be working openly on the ground in Syria.
US officials say President Barack Obama ordered the deployment of fewer than 50 commandos to help coalition forces coordinate with the local troops.
One official also says the US will be sending additional aircraft, including F-15 fighters and A-10s to the Incirlik air base in Turkey.
The officials were not authorized to discuss the matter publicly so spoke on condition of anonymity.
On Oct.30, Russian Deputy Foreign Minister Sergei Ryabkov said that Moscow considers the use of US forces without coordination with Syrian President Bashar Assad's government unacceptable.