DAMASCUS, June 27 (Xinhua) -- The U.S.-backed Syrian Democratic Forces (SDF) said Tuesday that capturing the city of Raqqa, the de facto capital of the Islamic State (IS) in northern Syria, is a matter of time.
The SDF, a collection of Kurdish, Arab and Assyrian fighters led by the Kurdish YPG group, said the IS is "obviously collapsing" in Raqqa, which has been under the wide-scale offensive of the SDF and U.S. airstrikes since June 6.
It said the IS is relying on counter-offensives using suicide bombers, which "reflect the collapse of the IS militants' morale."
The SDF said it blew up two booby-trapped vehicles which the IS militants were pushing into the Qadisiyeh neighborhood, the latest to be captured by the SDF.
It said hundreds of IS militants were "buried alive under the rubble in Qadisiyeh."
Heavily backed by the U.S.-led coalition, the SDF said the IS militants are completely surrounded in Raqqa, adding that tens of the terror militants are surrendering themselves secretly to the SDF forces.
Meanwhile, the Syrian Observatory for Human Rights said that 13 SDF fighters were laid to rest Tuesday after losing their lives in Qadisiyeh.
However, the SDF advance in Raqqa and the complete capture of the city won't be that easy, particularly with the Turkish threats.
Earlier this week, reports emerged by the observatory that Turkish military gears have entered northern Syria in preparation for a military showdown with the SDF, as Turkey wants to curb the advance of the SDF near the Turkish borders.
The observatory said in another report that the Turkish-backed Syrian rebels are preparing to launch an offensive against the SDF in the western countryside of Aleppo, which could affect the SDF offensive on Raqqa.
Other activists said the United States had deployed forces near the Tab Abyad town in Aleppo countryside to keep the Turkish-backed rebels away from the SDF.