Sources: Marines to Join Cave Search

Dec. 20 -- As many as 500 U.S. Marines could be on the way to an area where hundreds of al Qaeda and Taliban fighters made their last stand, sources told ABCNEWS.

The Marines would clean up whatever forces remain, a dangerous job given the chance of mines and booby-traps in the caves as well as possible snipers hiding in the mountains. But U.S. officials said they believe al Qaeda fighters remain in the steep canyons.

The task is being left to American troops because the many Afghan anti-Taliban fighters who helped subdue the Tora Bora mountaintop complex earlier this week have declared victory and appear to be preparing to go home.

Officials from the CIA and Defense Department are trying to convince tribal leaders to continue participating in the effort, by offering them money, winter clothing and equipment, sources said.

But American military sources said they still expect an enlarged American presence in the area.

"It is not [over] at all," said Kenton Keith, spokesman for the U.S.-led coalition in Islamabad. "Much of the military objectives have been achieved but not all. Hard work is going on. Whether it takes a day, a week or a year or how long will it take, it will continue until he [bin Laden] is brought to justice."

Until just days before al Qaeda resistance in the mountains collapsed, the Pentagon had strong indications that bin Laden was hiding in the caves, directing his terror network's resistance over shortwave radio. The question remains: Where did bin Laden and his top lieutenants disappear to?

There has been speculation that bin Laden either was killed or slipped across the border into Pakistan.

"You are indulging in kite-flying," Pakistan Foreign Ministry spokesman Aziz Ahmed Khan said when asked if it was possible that bin Laden was in Pakistan. "Anyone crossing the border illegally will be apprehended and will be dealt with according to the nature of offense."

Over the last two days, a number of Eastern Alliance commanders have accused one another of making deals to let top al Qaeda figures escape the region.