Kabul, Afghanistan ? A U.S. airstrike near the Pakistan border killed the Taliban’s southern military commander, a U.S. military spokesman said Saturday, calling him the highest-ranking Taliban ever slain by American forces.

Mullah Akhtar Mohammad Osmani’s vehicle was hit by a U.S. airstrike Tuesday as he traveled in a deserted area in the southern province of Helmand, the spokesman said. Two associates also were killed.

U.S. and Afghan officials said the strike was a major victory. Ahmed Rashid, a leading author on Islamic militancy, said Osmani’s death could disrupt planning for a Taliban offensive early next year, designed to extend the recent surge of violence across Afghanistan.

Osmani played an instrumental role in some of the Taliban’s most notorious excesses – including the demolition of the ancient Buddha statues in Bamiyan and the trial of Christian aid workers in 2001, Rashid said.

He was also one of three top associates of Taliban leader Mullah Omar, Rashid said, and among the first supporters of Osama bin Laden within the militant Islamic militia’s top ranks.

A Taliban spokesman denied that Osmani was dead. But a provincial police chief and Afghanistan’s Interior Ministry confirmed the killing. Interior Ministry spokesman Zemeri Bashary called it “a big achievement.”

A U.S. spokesman said the death was confirmed through multiple sources.

As the Taliban’s chief military commander in southern Afghanistan, Osmani played a “central role in facilitating terrorist operations” including roadside bombings, suicide attacks and ambushes against Afghan and international forces, said Col. Tom Collins, the U.S. military spokesman.

“Mullah Osmani is the highest ranking Taliban leader we’ve ever killed,” Collins said. “He was the chief of the Taliban’s military operations, so his death is very significant and will hurt the Taliban’s operations.”

Rashid agreed the death was a “major blow” to the militia.

“It’s the first casualty among the top Taliban leadership in the past five years, which makes the strike very significant,” he said.

Collins said Osmani had been “utilizing both sides” of the Afghan-Pakistan border, and that the U.S. military had been tracking him “for a while.”

“When the time was right, and we thought we had a good chance of hitting him without causing any harm to civilians, we struck,” he said.

The Taliban have stepped up attacks this year, especially in Afghanistan’s south, and waged fierce battles with Western and Afghan government forces.