March 27 (UPI) -- The Syrian Democratic Forces captured the Tabqa airbase in their offensive against the Islamic State to ultimately free the city of Raqqa.
The U.S.-backed Syrian Democratic Forces and its Syrian Arab Coalition fighters battled IS militants for about 24 hours before fully controlling the airbase on Sunday. The SDF also freed the desert villages of Abu Rashid and al-Ajil, which are near the airbase.
In a statement, the SDF said it killed 17 Islamic State militants in the battle for the airbase.
The SDF is advancing toward the city of Tabqa with the support of airstrikes carried out by the U.S.-led anti-Islamic State international coalition.
The Islamic State captured the Tabqa airbase in August 2014 after about 200 Syrian soldiers surrendered or fled when they ran out of ammunition. The Islamic state captured the soldiers and executed them in the Raqqa desert.
The Tabqa airbase is located about 25 miles west of Raqqa near the Euphrates River. The SDF, made up of Kurdish, Arab, Turkmen and Armenian militias, was established in October 2015 with the shared goal of battling the Islamic State.
The SDF is working to also capture the Tabqa dam, the largest dam in Syria which is a key source of electricity for the region.
The Islamic State said coalition airstrikes have caused the dam's gates to lock, leading water levels to rise and placing the dam at risk of collapse. Civilians living downstream have been told to evacuate, the Raqqa is Being Slaughtered Silently monitoring group said.
The U.S.-led international coalition -- named the Combined Joint Task Force: Operation Inherent Resolve -- said the dam had not been targeted by airstrikes.
"The Coalition is taking every precaution to ensure the integrity of Tabqah dam. To our knowledge, the dam has not been structurally damaged," the coalition said in a statement.
The SDF seeks to surround and isolate Raqqa before launching an offensive to recapture the city, similar to what Iraqi security forces did in their offensive on Mosul.
The SDF released a video showing part of the airbase's runways, which are damaged.