A US-backed Syrian force has begun an offensive to capture the northern city of Raqqa, the de facto capital of Islamic State, after months of clearing operations.
US Lieutenant General Steve Townsend predicts the fight for Raqqa will be long and hard, but the offensive would deliver a decisive blow to the idea of IS as a physical caliphate.
CJTF-OIR stated it issued multiple warnings before it destroyed "two artillery pieces and an anti-aircraft weapon" and damaged a tank.
This is the second time in a month that coalition forces have engaged pro-regime forces around al Tanf, where coalition advisers train local partners (and where United States and partner forces repulsed a fierce ISIS attack in April).
Officials said some pro-Assad forces likely remain in the area.
In a separate development a day earlier, the so-called Syrian Observatory for Human Rights said 21 civilians were killed during a U.S. airstrike while they were trying to flee the Daesh-held northern city of Raqqah, with reports that women and children were among the casualties.
"Morale is high and military readiness to implement the military plan is complete".
At least 21 civilians were killed Monday night in strikes by suspected US-led alliance warplanes in the city, the Observatory reported.
The U.S. dropped 90,000 brightly-colored leaflets more than a week ago, warning pro-Assad forces to leave the area and saying the coalition would take steps to defend itself.
The US-led coalition forces on Tuesday conducted a strike against pro-government forces in Syria that advanced inside the de-confliction zone in the southern part of the country, according to US military.
Col. Ryan Dillon, spokesman for the USA military's operations in Iraq and Syria against ISIS, told reporters during a phone briefing last week that the group outside the zone had built up its forces and combat power.
The convoy appears to have consisted not of regular Syrian army soldiers but of worldwide Shia militiamen.
The base is used by American and British commandos to train the rebels from the Free Syrian Army.