Islamic State insurgents have captured two northern Iraqi towns and an oil field in their first major victory over Kurdish fighters, witnesses said Sunday.
The al-Qaida offshoot, which swept through northern Iraq in June almost unopposed by Iraq's U.S.-trained army, poses the biggest challenge to the stability of the country since the fall of Saddam Hussein in 2003.
After thousands of Iraqi soldiers fled the Islamic State offensive, Shiite militias and Kurdish fighters have emerged as a key line of defense against the militants, who have threatened to march on Baghdad.