"It's possible that you may see conventional forces hit the ground in Syria for some period of time," one defense official told CNN.
But the official emphasized that any decision is ultimately up to President Donald Trump, who has ordered his defense secretary to come up with a proposal to combat ISIS before the end of the month.
The move would significantly alter US military operations in Syria if approved and could put troops on the ground within weeks.
Until now, only small teams made up largely of Special Operations forces have operated in Syria, providing training and assistance to anti-ISIS opposition groups on the ground.
Conventional units operate in larger numbers and would require a more significant footprint of security protection both on the ground and in the air.
US officials are characterizing the concept of deploying ground troops as a point of discussion, stopping short of saying it's a formal proposal.
What their exact mission would be is not yet clear, but one goal of their their presence would be to help reassure Turkey that Kurdish forces are not posing a threat to Ankara's interests. It's possible some troops would deploy first to Kuwait and then move into Syria.
The Obama administration never embraced the idea of ground combat troops because of the inherent risks involved. If the idea is approved, it would signal a fundamental change in the Trump administration's willingness to accept such risk.
For one thing, it would be a sign of an increased willingness by Defense Secretary James Mattis and Chairman of the Joint Chiefs Gen. Joseph Dunford to accept more risk for US troops in hope of gaining ground on ISIS.
At his confirmation hearing, Mattis was not asked about putting more troops into Syria, but he did explain how he would seek to change US military efforts in Iraq and Syria from Obama administration.
"I think it's getting there as rapidly as possible, where it would be a more accelerated campaign," Mattis said.
Sending troops to Syria is just one of several ideas that may be presented to the President, the official said.
Discussions are also underway on fundamentally changing how troops are deployed to Iraq.
The Obama administration established limits on how many troops could be in Iraq at any one time. As a result, troops have largely been deployed on an individual basis depending on how many trainers and advisers are needed.
Right now, no more than 5,262 troops are allowed in Iraq, with 5,155 there currently. There are hundreds more temporarily assigned that are not counted under the ceiling.
Trump may be asked to do away with all the limits so complete units can be sent and temporary deployments will also be counted. Commanders say this will give them more flexibility in operations, but it also will increase the number of troops there, something the Iraqi government would have to agree to.
Also under discussion is increased cooperation with the Russians and the arming of Kurdish groups in northern Syria supported by the US -- at the risk of angering Turkey.