NAWA, Afghanistan — U.S. Marines moved into villages in Taliban strongholds in southern Afghanistan today, meeting little resistance as they tried to win over local chiefs on the second day of the biggest military operation here since the fall of the Taliban government in 2001.

One Marine was killed and several others injured or wounded Thursday, when some 4,000 Marines launched the operation in Helmand province — a remote area in the center of the country's illegal opium cultivation, which helps finance the insurgency.

So far, however, there has been little resistance from the Taliban, according to a military spokesman Capt. Bill Pelletier.

Britain's Defense Ministry said a roadside bomb Wednesday in Helmand killed the most senior U.K. officer to have died in combat in Afghanistan. Lt. Col. Rupert Thorneloe was the commanding officer of the 1st Battalion Welsh Guards.

The aim of the operation in Helmand is not simply to kill Taliban fighters but to win over the population, Pelletier said.

"We are not worried about the Taliban, we are not focused on them. We are focused on the people," Pelletier said. "It is important to engage with the key leaders, hear what they need most and what are their priorities."

The offensive will test the Obama administration's new strategy of holding territory to let the Afghan government sink roots in rural areas where Taliban influence is strong.