Several hundred marines have deployed into Syria with artillery guns, as part of the ongoing preparation for the fight to push ISIL out of its self-declared headquarters of Raqqa, a Pentagon spokesman has confirmed.
The marines are pre-positioning howitzers to be ready to assist local Syrian forces, according to US officials.
The deployment is temporary. But it could be an indication that the White House is leaning towards giving the Pentagon greater flexibility to make routine combat decisions in the fight against the Islamic State of Iraq and the Levant (ISIL/ISIS).
Military commanders frustrated by what they considered micromanagement under the previous administration have argued for greater freedom to make daily decisions on how best to fight the enemy.
In addition, the US is preparing to send up to 1,000 troops to Kuwait to be ready to join the ISIL fight if they are needed, officials said.
Proponents of the move said it would provide US commanders on the ground with greater flexibility to quickly respond to unforeseen opportunities and challenges on the battlefield.
The latest troop movements come on the heels of the recent temporary deployment of some dozens of army forces to the outskirts of Manbij, Syria, in what the Pentagon called a "reassure and deter" mission.
Flying American flags and moving in large, heavily armoured vehicles, the troops were there to keep a lid on tensions in the area, the Pentagon said.
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Under the existing limits put in place by the Obama administration, the military can have up to 500 US forces in Syria, although temporary personnel do not count against the cap.
The special operations fighters are ostensibly there to train and assist the Syrian Democratic Forces, an umbrella group of Kurdish and Arab fighters that have proven to be a key ground asset in the US-led coalition's battle against ISIL.
Pentagon leaders sent a new plan to defeat ISIL to the White House late last month. It outlined a strategy that would likely increase the number of US troops in Syria in order to better advise and enable the US-backed Syrian fighters who will take on the battle for Raqqa.
The military has mapped out a series of options for the Syria fight, including increased artillery support, more Apache helicopters and a more robust training campaign.
US officials say the battle for Raqqa will look much like the fight in neighbouring Iraq, where local forces are in a fierce battle to retake the northern city of Mosul - ISIL's last stronghold in the country.
As troops were preparing to move into Mosul, the US set up bases outside the city to use as logistical hubs and as locations for heavy artillery.
The moves to pre-position US troops closer to the fight, so they can be tapped as needed, are the kinds of decisions that military commanders say they need to be able to make more quickly, without going to the White House every time for approval.
Source: News agencies