WASHINGTON, Oct 15: US military targets in Afghanistan now include troops, specifically the Taliban’s Brigade 55, an elite unit that includes Arab fighters loyal to Osama bin Laden, officials and experts said on Monday.

“I’m not going to get into a particular case, but I think that people should be on notice that it is not trees or rocks that cause terrorism, it’s people,” the US Secretary of Defense said.

Rumsfeld refused to confirm that US airplanes had tracked Taliban supreme leader Mullah Mohammad Omar, whose US-made all-terrain vehicle was recently destroyed by a US missile.

Rumsfeld had been angry to learn that US intelligence had let slip an opportunity to kill Omar after he was located by a pilotless CIA spy plane on Oct 7, the first day of the US bombing of Afghanistan, the New Yorker magazine reported.

But he has made it clear that in days to come the US bombardment will focus less on known targets and more on so-called opportunity targets.

“The United States is seeking out concentrations of people who are involved in these terrorist activities and in the terrorist training camps and in the terrorist network. And when we find them, we do try to deal with them,” Rumsfeld said.

A Pentagon official speaking on condition of anonymity named the elite Brigade 55 unit as one of the most sought-after targets.

The 500-strong unit forms the heart of forces loyal to Osama, whom the United States holds responsible for suicide attacks against the United States on September 11, the official said.

The United States estimates that Osama’s forces in Afghanistan number between 1,500 and 4,000 individuals of diverse Arab nationalities — mostly Egyptians, Saudis and Yemenis.

“The Arab ‘volunteers’ are concentrated in the 55th brigade. There has been a lot of exaggeration about the number and military significance of these fighters,” said Ali Jalali, a former Afghan army colonel.

“It is not the size but the political impact of the unit that affects the Afghan battlefield,” Jalali wrote in “Parameters,” a magazine on US army strategy.

For Richard Kidd, a retired army captain who has worked in UN anti-landmine efforts in Afghanistan, Osama’s forces protect senior Taliban leaders and have built them a system of deep bunkers designed to withstand cruise missile strikes.

“His forces basically rule the southern city of Kandahar,” Kidd said.

Pentagon officials say that al-Qaeda fighters are reinforcing Taliban forces to boost the morale of soldiers whose loyalty to the Taliban regime is in danger of eroding as the US military campaign continues.—AFP