MARJAH, Afghanistan — Marines and Afghan troops essentially secured the former Taliban-ruled town of Marjah on Saturday — part of an offensive that is the run-up to a larger showdown this year in the most strategic part of Afghanistan’s dangerous south.

Although Marines say their work in Marjah isn’t done, Afghans are bracing for a bigger, more comprehensive assault in neighboring Kandahar province, the birthplace of the Taliban, where officials are talking to aid organizations about how to handle up to 10,000 who could be displaced by fighting.

“I was in Kabul, and we were talking that Kandahar will be next, but we don’t know when,” said Tooryalai Wesa, the governor of Kandahar. He’s begun working with international aid organizations to make sure the next group of displaced Afghans has tents, water containers, medicine, food, blankets, lamps and stoves.

“Hopefully, things will go smoothly, that people have learned lessons from the Marjah operation,” he said.

Shortages of food and medicine have been reported during the 2-week-old Marjah operation. The Red Cross evacuated dozens of sick and injured civilians to clinics outside the area. The U.N. says more than 3,700 families, or an estimated 22,000 people, from Marjah and surrounding areas have registered in Helmand’s capital of Lashkar Gah 20 miles away.