More than two months into its assault on Kobani, the Islamic State group is still pouring fighters and resources into trying to capture the besieged Syrian Kurdish town, but the drive has been blunted.

Helped by more than 270 airstrikes from a U.S.-led coalition, the border town’s unwavering Kurdish defenders are gaining momentum – a potentially bruising reversal for the extremists who only a few weeks ago appeared to be unstoppable.

The setback in Kobani is “a statement of IS group’s vulnerability,” said David L. Phillips, an expert on Kurdish issues. […]