The troops will reportedly be deployed in the YPG-controlled territory in northern Syria and are not expected to be on the front lines unless authorised by Washington.
The US is stepping up its presence in Syria after deploying another 1,000 troops in an attempt to drive Daesh out of Raqqa, the group's de-facto capital in the country.
Last week, the US-led coalition announced that about 400 US forces had been deployed to Syria to help with the Raqqa campaign.
They also want to prevent any clash between Turkish-backed opposition forces and the US-allied YPG.
While the US considers the YPG to be an ally in the fight against Daesh, Turkey considers the group to be a branch of the PKK, which both Ankara and Washington list as a terrorist organisation.
TRT World's Patrice Howard has more details on the US deployment.
At the beginning of March, the US deployed Marines armed with heavy artillery to Syria ahead of the Raqqa offensive.
The move came just days after the Pentagon announced the deployment of dozens of US ground troops on the outskirts of the YPG-controlled town of Manbij.
The Pentagon had said the deployment to Manbij would serve as a "visible sign of deterrence and reassurance," in what appears to be an attempt to ensure that the Turkish-backed Free Syrian Army (FSA) opposition forces do not clash with the US-backed YPG.
A senior US official at the time said deployed Marines are "pre-positioning howitzers to be ready to assist local Syrian forces," without referring to a specific group.
The official also said that hundreds of Marines would also be deployed to Kuwait, where they will remain on standby to be called into action against Daesh if necessary.
Expanded US role
US military commanders in Syria were restricted by what critics considered micro-management under the previous administration of Barack Obama. They want greater freedom and flexibility to make daily combat decisions without going to the White House for approval every time.
Existing restrictions limit the US to stationing no more than 503 forces permanently in Syria.
But in a letter to the White House last month, Pentagon leaders appealed for an increase in order to better advise allied fighters ahead of the battle for Raqqa.
They also requested increased artillery support, more Apache helicopters, and a more robust training campaign.
Raqqa is Daesh's de facto capital in Syria. The terrorist group occupied the city in 2013 in a security vacuum resulting from the Syrian civil war.
The group expanded in 2014, capturing the Iraqi city of Mosul and declaring a "caliphate" in the region.
A multi-front battle ensued, and Daesh has lost ground on both sides of the border, even as the civil war rages on in Syria.