Hundreds of troops from the 3rd Battalion, 4th Marines and the Marine reconnaissance unit Task Force Raider were dropped by helicopter and MV-22 Osprey aircraft behind Taliban lines in the northern end of the Now Zad Valley of Helmand province, scene of heavy fighting last summer, according to Marine spokesman Maj. William Pelletier.
A second, larger force pushed northward from the Marines' Forward Operating Base in Now Zad, Pelletier said. Combat engineers were forcing a corridor through Taliban minefields with armored steamrollers and explosives, Pelletier said.
In all, about 1,000 Marines as well as Afghan troops were taking part in the operation, known as "Cobra's Anger," he said.
There were no reports of casualties.
The operation began three days after Obama announced that he was sending 30,000 reinforcements to Afghanistan to help turn the tide against the Taliban. America's European allies will send an estimated 7,000 more troops to Afghanistan next year "with more to come," NATO chief Anders Fogh Rasmussen announced Friday.
Most of the new troops are expected to be sent to southern Afghanistan, including Helmand, where Taliban influence is strongest.
The new offensive aims to cut off the Taliban communication routes through Helmand and disrupt their supply lines, especially those providing explosives for the numerous lethal roadside bombs that litter the area.
Pelletier said several arms caches and at least 400 pounds of explosive materials had been found so far Friday.
"Right now, the enemy is confused and disorganized," Pelletier said by telephone from Camp Leatherneck, the main Marines base in Helmand. "They're fighting, but not too effectively."
Pelletier said insurgents were caught off guard by the early morning air assault, the first using Ospreys, an aircraft that combines features of helicopters and fixed wing aircraft.