Fighters from the U.S.-backed Syrian Democratic Forces crossed the Euphrates by boat and helicopter March 22, landing near the village of Abu Hurayrah in Raqqa province, Kom News reported. The assault was backed by U.S.-led coalition airstrikes against nearby Tabqa city, which is controlled by the Islamic State. The Tabqa Dam, also known as al-Thawra, is Syria's largest. The United States has confirmed the new offensive, which it says is aimed at retaking the dam. The action takes place as part of the run-up to the impending assault to retake Raqqa city, the Islamic State's de facto capital. Reports also emerged March 22 that an airstrike hit a school in Raqqa province late on March 20, killing more than 30 people. Activists said the site was sheltering displaced people at the time of the strike, blaming it on the U.S.-led coalition. It is still not completely clear who carried out the strike.