Afghanistan ? Minivans piled high with mattresses and clothing lined up at checkpoints Sunday as hundreds of civilians fled a Taliban-controlled area ahead of a planned NATO offensive in southern Afghanistan.

The militants, meanwhile, dug in for a fight, reinforcing their positions with rocket-propelled grenades and heavy weapons, according to witnesses.

The U.S. military has not given a start date for the operation to clear insurgents from the Helmand province town of Marjah, the biggest community in the south under insurgent control. But the military has said fighting will start soon and many residents weren’t taking any chances.

American aircraft dropped leaflets over Marjah on Sunday warning people of the coming offensive, officers said, and the U.S. fired illumination rounds after sundown, apparently to help spot Taliban positions.

Villagers said the leaflets were aimed primarily at the militants, listing several of their commanders by name and warning fighters to leave the area or be killed.