Col. Brian Tribus, a spokesman for General Campbell, said the raid had been conducted “to destroy a cache of munitions that could be used to conduct attacks against Afghans and coalition forces.”

The raid on Mr. Ahmad’s home, roughly three miles from Parwan’s provincial center, was carried out around 4:30 a.m. and involved United States forces descending from helicopters, an aide to Mr. Ahmad said on the condition of anonymity, as he was not authorized to speak to the news media. After searching the home, the soldiers blew up the depot.

Mr. Ahmad’s aide said the depot dated from the fight against the Soviets in the 1980s and did not have new weapons, but American and Afghan officials disagreed.

The largest United States base in Afghanistan, Bagram Air Base, is in Parwan Province and has come under frequent rocket fire in recent months. While those rocket attacks have been attributed to the Taliban, and not commanders like Mr. Ahmad, the presence of a weapons cache so close to an American base was seen as a threat.

“It was a lot of weapons — it must have been a lot to make the foreigners fearful and force them to take action,” said Hajji Khalil Fazly, a member of the Parwan provincial council who was involved in the negotiations between the government authorities and Mr. Ahmad to calm the protests. Protesters were cleared, and the highway reopened by noon, he said.

It was not the first time in recent months that American troops had gone after a local strongman not linked to the Taliban. In March, Afghan officials said a night raid on the outskirts of Charikar, carried out by Afghan and United States forces and involving American drones, had targeted Hashmatullah, leader of a small armed group said to be associated with Mr. Ahmad. The attack left three people dead and four wounded, but Hashmatullah, known as Commander Hasho, survived with minor wounds.

Elders in Parwan say the Afghan government has also increased scrutiny of strongmen in recent months on charges of hiding caches of weapons. Government spokesmen have often expressed concern about “irresponsible militias” that have evaded multiple disarmament campaigns. That fear has only increased in recent months with reports of old anti-Taliban commanders rearming on the pretext of self-defense as the threat from the resurgent militants grows across the country.