U.S. Marines and Afghan troops Friday launched the first offensive since President Barack Obama announced an American troop surge, striking against Taliban communications and supply lines in a southern insurgent stronghold, a military spokesman said.

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.