It’s oil or nothing. Hours after Iraqi forces and Shia militias launched an operation to recapture oil fields and a military base near Kirkuk from Kurdish Peshmerga fighters, they reportedly seized the key city. Last month, an independence referendum passed by an overwhelming margin in northern Iraq, raising fears in Baghdad that Kurdistan’s secession is imminent. The new country would include Kirkuk, which has a mixed Arab and Kurdish population, and valuable nearby oil fields. Meanwhile, thousands of people have fled the disputed city — controlled since 2014 by Peshmerga forces — amid the Iraqi advance.