Updated

The trail has gone cold in the hunt for suspected Sept. 11 mastermind Usama bin Laden (search) three years after the audacious attacks, but the Al Qaeda (search) chief and his No. 2 are still orchestrating strikes like the recent homicide car bombing of a U.S. security firm in Kabul, a top American commander said Saturday.

Maj. Gen. Eric Olson told The Associated Press the military had not intercepted any radio traffic or instructions from either bin Laden or his deputy, Ayman al-Zawahri (search). But he said the involvement of well-trained foreign fighters in attacks near the Pakistani border convinced him that the fugitive leaders were pulling the strings.

"What we see are their techniques and their tactics here in Afghanistan, so I think it is reasonable to assume that the senior leaders are involved in directing those operations," Olson, the operational commander of U.S.-led forces in Afghanistan, said in an interview.

The Aug. 26 car bomb which killed about 10 people, including three Americans, at the office of a firm providing bodyguards for President Hamid Karzai also bears the hallmarks of the militant network, Olson said.

"We've even tied it to a group that has ties to Al Qaeda. It could be a splinter group of some sort," Olson told AP after a ceremony at the U.S. base at Bagram north of Kabul to mark the third anniversary of the Sept. 11, 2001, attacks.

"It's a new group, apparently a group that was carved from Al Qaeda," he said. "They have members in Pakistan and they have been active in Afghanistan, and this recent attack is the most blatant example." He declined to elaborate.

There were reports Saturday of fresh fighting in the country, where more than 900 people -- mostly Afghan security forces and rebels -- have died in political violence this year.

In the troubled southern province of Zabul, Afghan officials said two Arabs were killed and two more captured in a firefight with U.S. and Afghan troops, and that Taliban gunmen killed two elders for supporting the government. In neighboring Kandahar, eight Taliban fighters and three Afghan soldiers were reported killed in two more incidents.

Olson, a native of New York City, addressed some of the 18,000 mainly U.S. troops he commands. About 300 soldiers had gathered in a dusty tent to hear readings from the Bible and the Quran, patriotic songs and speeches reminding them of their mission.

Some wept as they watched videos of how the hijacked jetliners felled the World Trade Center towers in New York and devastated a wing of the U.S. Department of Defense three years ago.

"We're here to prevent future ceremonies, future Sept. 11s," said Maj. Andy Preston, an infantryman from Edmond, Okla., who was working at the Pentagon when it was hit.

The U.S. invasion of Afghanistan that followed, Operation Enduring Freedom, quickly routed the government of the hardline Taliban movement and scattered the Al Qaeda fighters and leaders it harbored. The Taliban has regrouped and sustained an insurgency across the south and east of the country, which Olson said was supported also by foreign fighters.

Olson said some militants attacking U.S. forces along the Pakistani border with mortars and rockets expertly adjust their aim -- betraying a level of training not commonly seen among Taliban fighters.

Arabs, including Saudis and Yemenis, were among fighters recently detected in Kandahar province. Russian chatter was intercepted by radio monitors in the former Al Qaeda stronghold of Khost, suggesting Chechen and Uzbeks were operating there, he said.

The Pakistani army has carried out a string of bloody raids on its side of the border in an area considered a possible hide-out for bin Laden. Olson praised the "very successful" Pakistani operations, but suggested that only political and economic developments in Afghanistan could defeat the insurgency.

American and Afghan officials predict that militant attacks which have also killed dozens of aid workers and government officials will intensify with the approach of Oct. 9 presidential elections.

"I don't think we're close at all" to defeating the insurgents, Olson said, but insisted organizing a successful vote could convince many opponents to give up the fight.

He said six key allies of renegade Afghan warlord Gulbuddin Hekmatyar and a group of senior Taliban had recently indicated their willingness to "come over" to the government side -- a prize long-sought by Karzai.

Piloting through the elections "makes a very powerful statement," said Olson. "They'll want to join rather than fight."