Iraqis fleeing from Falluja question whether the masked gunmen who overran their city 10 days ago are really al Qaeda-linked militants as the government says, but fear their presence will draw a ferocious response from the army regardless.

At a motel in Iraq’s Kurdish north, Falluja residents said they were stunned by the speed of the takeover of the city in Sunni-dominated Anbar province, predicting a tough fight if the Shi’ite-led government orders troops to retake it.

Al Qaeda-linked militants, who are also fighting in neighboring Syria, have been regaining ground over the past year in Anbar, which they seized in 2006-07 before being forced out by local tribal militia and occupying U.S. troops. […]