Kurdish forces in Syria say deepening military coordination with the United States and its allies has helped them make rapid advances against Islamic State in an offensive under way in the northeast near the border with Iraq.

The Kurdish People’s Protection Units (YPG) have seized two towns and dozens of villages from Islamic State (IS) in an offensive that got under way on Feb. 21 in the strategically important Hasaka province that borders IS-held areas in Iraq.

The advance, which has cut at least one Islamic State supply route from Iraq, has moved much faster than the campaign for Kobani, where it took the YPG aided by Iraqi Kurdish fighters and U.S.-led air strikes some four months to defeat IS. […]