The US military provided air and artillery support in an offensive for a dam near the ISIS stronghold of Raqqa in Syria.

The US military provided air and artillery support – and transported local forces – in an offensive for a vitally important dam near the ISIS stronghold of Raqqa in Syria, officials said Wednesday.

Tabqa Dam at the southern end of Lake Assad is about 35 miles (55 kilometers) west of Raqqa, which ISIS views as its capital. The ISIS-held facility provides electricity to much of the region and its destruction would result in widespread flooding.

Colonel Joseph Scrocca, a spokesman for the US-led coalition helping local fighters, said US support came overnight Tuesday-Wednesday via Apache helicopter gunships, airlifts, air strikes and advice to the Syrian Democratic Forces, an Arab-Kurdish alliance. A US Marine artillery battery is also helping out.

In a first, US forces helicoptered an unspecified number of Arab SDF troops to Taqba, meaning they are now behind ISIS lines as they try to secure the dam. Scrocca said the area around it is effectively a “command and control center for terrorist attacks against the West” and home to numerous foreign fighter training camps.

A strategic advantage

“Seizing Tabqa will give the SDF a strategic advantage and a launching point needed for the liberation” of Raqqa, Scrocca said. The SDF has been working for months to encircle Raqqa before pushing into the city proper.

Scrocca said the military is probing claims that a US-led strike killed dozens of civilians. A suspected coalition air raid hit a school being used as a temporary shelter for displaced families between Raqqa city and Tabqa.

The Syrian Observatory for Human Rights, a monitoring group, said a coalition air strike early Tuesday killed 33 displaced civilians near the town of Al-Mansura, about 20 miles west of Raqqa. “In preparation for this operation, the coalition conducted several strikes near Raqa in that area,” Scrocca said.

“We will take a look at that allegation and determine its credibility.” The coalition estimates that between 3,000 and 4,000 militants are in Raqqa, a city of about 300,000. The battle to retake the city is expected to be brutal.