Al-Qaida plots comeback in Afghanistan: US

"Not having US forces in Afghanistan would embolden these groups and be counterproductive for US national security," he said.

Those tracking al-Qahtani say he has survived by following some of the same rules that helped Osama bin Laden avoid capture for so many years: He stays off cellphones and radios to hide from spy satellites and airborne radars, instead using couriers or face-to-face meetings, and he stays on the move.

When he travels to populated areas, he stays among women and children, which he knows the US will avoid striking.

The local tribesmen do not aid the US effort, nor does the barren, mountainous terrain where incoming raiders are visible for miles.

"When helicopters went in, you can hear the whistles go up," from the villages, echoing across the valleys and sending militants fleeing for cover, one of the US military officials said.

The officials say US special operators have all but given up capturing al-Qahtani and have traded fruitless and dangerous helicopter-borne raids for air strikes by drone and jet, averaging three to five a week.

To their knowledge, they have never come close to striking him.

The reports give added ammunition to a comprehensive intelligence analysis on Afghanistan completed in December.

The report predicted the country will largely disintegrate along ethnic lines after the US departs, with the central government controlling Kabul and a few other key cities.