HELMAND PROVINCE, Afghanistan -- The last time the U.S. Marines were here, a force of 20,000 all but drove the Taliban out of their stronghold of Helmand Province, reports CBS News foreign correspondent Charlie D'Agata.

Back then, Brig. Gen. Roger Turner was a colonel.

"Did you think you'd be back here?" D'Agata asked.

"No I didn't, I didn't really. I left here in 2012 and we knew that the mission was going to end in 2014 so I didn't think I'd be back here," Turner said.

This time, his mission is dramatically different. He's in command of just 300 Marines, training Afghans to fight for themselves.

This is the first time in several years that U.S. Marines are on the ground in the province.

Brig. Gen. Roger Turner CBS News

D'Agata and his crew joined the Marines as they flew over what is once again Taliban-held territory. Because not long after the Marines pulled out, the Taliban swept through Helmand, recapturing territory U.S. forces fought and died for, with 349 American lives lost.

The fight will now be led by Afghan Brig. Gen. Wali Mohammed Ahmedzai, who stressed the urgent need for increased American support to defeat the Taliban.

Brig. Gen. Wali Mohammed Ahmedzai CBS News

"This war is not just ours," Ahmedzai said. "It's a war against international terrorism. We need Americans' advanced technology, and more forces to fight with us."

But Turner said the Marines' role is simply to train, advise and assist. The priority is to get Afghans to do the fighting.

"I don't know that having Marines right behind them is something we'd need to do," he said.

Recapturing -- and holding onto -- Taliban-held territory is a task Afghan forces must take on themselves, eventually on their own.

The Afghans are making progress. On Monday, they recaptured a strategic town near the provincial capital, with the help of U.S. forces.

But the question is whether this time they can hold onto it, and for how long.