“The Taliban should consider intensifying peace talks, not the fight,” Sgt. First Class Debra Richardson, a spokeswoman for the United States forces in Afghanistan, said, confirming that Mullah Manan had been killed by an American airstrike.

“They’re going to have trouble intensifying the fight when their fighters and leaders are under constant assault. Peace talks are the only solution,” she added.

Bashir Ahmad Shakir, who until recently was the head of the security committee at Helmand’s provincial council, described Mullah Manan as a “fighting machine.”

“He was tough and a good manager of the battlefield,” Mr. Shakir said. “I remember there were times where he would engage the Afghan forces in 12 different places in Helmand simultaneously.”

Mullah Manan’s death comes as the Taliban are pushing for further gains in the south, following the assassination of the general leading the government’s defenses there. Gen. Abdul Raziq, the police chief of Kandahar Province and a major anti-Taliban bulwark, was gunned down in an attack last month that barely missed the top American commander, Gen. Austin S. Miller.