Hundreds of US Marines armed with heavy artillery have arrived in Syria to help allied local forces in preparation for an offensive to recapture the city of Raqqah from Daesh terrorists, officials say.
Marines from the San Diego-based 11th Marine Expeditionary Unit have deployed a battery of 155mm Howitzers to an outpost in Syria and "are ready to conduct their mission," a US official told AFP on Thursday.
The deployment marks a significant move for conventional US forces in Syria, which have been limited to about 500 Special Operations forces on the ground.
Air Force Colonel John Dorrian, spokesman of the coalition purportedly fighting Daesh, said the additional forces, comprising a total of 400 Marines and Army Rangers, would be working with the so-called Syrian Democratic Forces (SDF) and the Syrian Arab Coalition.
Dorrian told Reuters that the artillery battery would help "expedite the defeat" of Daesh in Raqqah.
"We have had what I would describe as a pretty relentless air campaign to destroy enemy capabilities and to kill enemy fighters in that area already. That is something that we are going to continue and intensify with this new capability," he said.
The move reflects tactics ahead of the assault on the Iraqi city of Mosul, where the US established bases outside the city as a platform for logistics and heavy artillery.
The SDF, which includes the Kurdish People's Protection Units (YPG), is the main US partner on the ground in Syria and has been fighting Daesh for months around Raqqah, the de facto capital of the terrorist group in the country.
Over the weekend, a separate force of elite US Army Rangers arrived in a town north-west of Raqqah in armored vehicles to head off a confrontation between Turkish and Syrian Kurdish fighters - both US allies.
The deployment was the first of its kind by the US in Manbij.
In a proposal presented to the White House last week, the Pentagon called for a significant increase in US military engagement in Syria including more Special Operations forces, attack helicopters and artillery.
Military planners proposed lifting the cap on military force level in Syria.
US officials say the troops would not be directly involved in ground combat. However, the proposal would allow them to operate closer to the front line and would delegate broader authority down the military line from the White House before an operation is launched.
Turkey has warned of a major damage to US relations with Ankara if Washington includes Kurdish forces in the Raqqah operation.
Turkey views the YPG as a threat to its national security and has threatened to strike the Kurdish forces if they maintain their presence in Manbij.