Syrian Kurdish forces advanced against Islamic State fighters in two separate attacks in northeastern Syria near the Iraqi border on Sunday, an organization tracking the war reported, compounding recent losses for the militant group in Syria.

The Kurdish YPG militia has been one of Islamic State’s toughest enemies in Syria and last month flushed the group out of the town of Kobani with the help of U.S. and allied air support and Iraqi Kurdish reinforcements on the ground.

Hasaka province in the northeastern corner of Syria is strategically important in the fight against Islamic State because it borders areas controlled by the group in Iraq. […]