President Barack Obama is bolstering US allies in Syria by sending commandos to rebel-held territory in a bid to edge out Russian supported forces of Syrian President Basher al-Assad.
The United States will deploy dozens of special operations troops to northern Syria from next month to advise opposition forces in their fight against Islamic State.
The US decision to deploy special forces along with the inclusion of Iran in diplomatic efforts to end the conflict is seen as a major policy shift aimed at resisting Russian involvement in the conflict.
The Obama administration has long resisted getting dragged into another war in the Middle East. But that policy has changed now that Russia is engaging government forces to battle both IS and rebel forces in Syria.
Announcing the measure on Friday, the White House said the troops would be on a mission to "train, advise and assist" and would number fewer than 50. Spokesman Josh Earnest declined to give details about their exact role.
US officials stressed the forces were not meant to engage in front-line combat.
"This is a dangerous place on the globe and they are at risk, and there's no denying that," said Earnest.
The spokesman, however, did not rule out the possibility of sending additional special forces into Iraq.
Obama also spoke to Iraqi Prime Minister Haider al-Abadi on Friday about the fight against Islamic State, Earnest said.
The Obama administration is under pressure to ramp up US military programme to train and arm thousands of Syrian rebels and bolster defences against Islamic State, particularly after the militant group captured the Iraqi city of Ramadi in May.
The planned deployment could increasingly complicate an already volatile conflict in Syria, where Russia and Iran have increased their military support for President Bashar al-Assad's fight against US-backed rebels in an ongoing civil war.
Russia said when it began air strikes last month that it would also target the Islamic State militant group, but its planes have hit other rebel groups opposed to Assad, including groups backed by Washington.
US defence secretary Ash Carter said on Friday agreed that the decision to send US special forces to Syria will put US forces "in harm's way,", although he did not rule out the possibility of sending additional special forces to Syria.