US military spokesman says siege of Raqqa coming

A U.S. military spokesman says the U.S.-led coalition and its allies are paving the way to storm the northern Syrian city of Raqqa, the de facto capital of the Islamic State group.

Col. John L. Dorrian, told reporters in Baghdad Tuesday that "ultimately we're isolating Raqqa and we are going to, at a time that our partners choose, move in and liberate that city from" ISIS.

The U.S.-backed Syrian Democratic Forces has been on the offensive since November capturing territory with the aim of laying siege to Raqqa. The city now is surrounded from three sides.

Dorrian said the operation to liberate Raqqa is the equivalent in Syria of what's being "done to eliminate the enemy" in the northern Iraqi city of Mosul.