Near Marjah, Afghanistan ? U.S. and Afghan forces pushed Tuesday to the edge of the southern Afghan town of Marjah, poised to seize the major Taliban supply and drug-smuggling stronghold in hopes of building public support by providing aid and services once the insurgents are gone.

Instead of keeping the offensive secret, Americans have been talking about it for weeks, expecting the Taliban would flee. But the militants appear to be digging in, apparently believing that even a losing fight would rally supporters and sabotage U.S. plans if the battle proves destructive.

No date for the main attack has been announced but all signs indicate it will come soon. It will be the first major offensive since President Barack Obama announced last December that he was sending 30,000 reinforcements to Afghanistan, and will serve as a significant test of the new U.S. strategy for turning back the Taliban.

About 400 U.S. troops from the Army’s 5th Stryker Brigade and about 250 Afghan soldiers moved into positions northeast of Marjah before dawn Tuesday as U.S. Marines pushed to the outskirts of the town.

Automatic rifle fire rattled in the distance as the Marines dug in for the night with temperatures below freezing. The occasional thud of mortar shells and the sharp blast of rocket-propelled grenades fired by the Taliban pierced the air.

“They’re trying to bait us, don’t get sucked in,” yelled a Marine sergeant, warning his troops not to venture closer to the town. In the distance, Marines could see farmers and nomads gathering their livestock at sunset, seemingly indifferent to the firing.

The U.S. goal is to take control quickly of the farming community, located in a vast, irrigated swath of land in Helmand province 380 miles southwest of Kabul. That would enable the Afghan government to re-establish a presence, bringing security, electricity, clean water and other public services to the estimated 80,000 inhabitants.

Over time, American commanders believe such services will undermine the appeal of the Taliban among their fellow Pashtuns, the largest ethnic group in the country and the base of the insurgents’ support.

“The military operation is phase one,” Helmand Gov. Gulab Mangal told reporters Tuesday in Kabul. “In addition to that, we will have development in place, justice, good governance, bringing job opportunities to the people.”

Marjah will serve as the first trial for the new strategy implemented last year by the top U.S. commander in Afghanistan, Gen. Stanley McChrystal. He maintains that success in the eight-year conflict cannot be achieved by killing Taliban fighters, but rather by protecting civilians and winning over their support.

Many Afghan Pashtuns are believed to have turned to the Taliban, who were driven from power in the U.S.-led invasion of 2001, because of disgust over the ineffectual and corrupt government of President Hamid Karzai.

“The success of the operation will not be in the military phase,” NATO’s civilian chief in Afghanistan, Mark Sedwill, told reporters Tuesday. “It will be over the next weeks and months as the people … feel the benefits of better governance, of economic opportunities and of operating under the legitimate authorities of Afghanistan.”