CAMP DWYER, Afghanistan: Thousands of US Marines poured into Afghanistan’s Taleban heartland yesterday, quickly capturing a district in the first major assault of President Barack Obama’s new war plan.

Dozens of aircraft ferried out the Marines from bases before dawn, aiming to take control of insurgent bastions of Helmand province in the country’s south ahead of landmark Afghan elections next month.

Involving nearly 4,500 Marines and US sailors the air-and-ground assault was their first major operation since they arrived in Afghanistan as part of Obama’s aggressive new strategy to turn the tide on a dragging conflict with the Taleban.

Within hours, Marines and Afghan troops had hoisted the Afghan flag in the southern Khanishin district, entering the main town with no resistance, Afghan commanders said. “The enemy has fled,” Afghan Army Corps Cmdr. Gen. Shair Mohammad Zazai said.

Khanishin, not far from the border with Pakistan, was one of a handful of districts in opium-growing Helmand where the Taleban held sway, establishing a proxy administration and justice system.

Pakistan’s military said it had redeployed troops along the Afghan border to prevent Taleban fighters from fleeing the offensive.

But the Marines also counted their first fatality with one killed in “hostile fire,” spokesman First Lt. Kurt Stahl said without providing details. “The helicopter insert has put all troops on the ground now in Garmser and Nawa,” Stahl said, referring to districts that are key targets of the assault in the desert.

“Half the objective has been secured by nightfall, ahead of schedule. Slight resistance has been met,” he said. The operation was dismissed by the Taleban, with the Afghan Islamic Press quoting a spokesman as saying that previous operations had not yielded success for the armed forces. “We are resisting but would adopt all kinds of war tactics to the situation,” spokesman Yousaf Ahmadi was quoted as telling the agency.

Called Khanjar, which means dagger in Dari and Pashto, the operation also involved about 650 Afghan police and soldiers. “What makes Operation Khanjar different from those that have occurred before is the massive size of the force and its speed,” Marine Cmdr. Brig. Gen. Larry Nicholson said.

The US military later said that a soldier had been missing in southeastern Afghanistan since Tuesday, before the operation in Helmand began, and was thought to have been captured by militants. The Pentagon confirmed the incident.

A Taleban commander, Mullah Sangeen, said by phone from an undisclosed location the soldier was taken as a patrol walked out of its base in Paktika province. ¬