U.S. defense officials are using a variety of high-tech tools to hunt down Osama bin Laden and other al-Qaida and Taleban leaders.
Pentagon officials like to say that al-Qaida terrorist leader Osama bin Laden may try to hide, but that he cannot escape - whether he seeks sanctuary deep in an Afghan cave or tries to flee to some other country.
Pentagon Spokeswoman Victoria Clarke puts it this way:
"We are focused hard on trying to make sure Osama bin Laden and others cannot go fleeing to other places and cause trouble," she said.
The preventative measures include such obvious measures as border patrols, reconnaissance flights and even ship searches off the coast of Pakistan.
The United States has also posted a multi-million dollar reward for information leading to Osama bin Laden's capture - a move that officials say has yielded scores of tips.
But inside Afghanistan, U.S. military personnel are using what one source describes as every possible tool to track down al-Qaida and Taleban leaders.
These include sophisticated sensing devices that can detect people or objects by penetrating through the ground, foliage, bad weather and darkness.
The devices operate by detecting motion, heat, electronic signals, magnetic fields and more. They can be mounted on aircraft or on vehicles or even hand carried by a soldier.
Pentagon officials are reluctant to go into great detail about the various sensor capabilities.
But it is known that at least some of these devices are mounted aboard unmanned spy planes. One of these, called Predator, is being flown in Afghanistan armed not only with sensors but also with Hellfire missiles.
Officials say that means Predator not only has a chance to find Osama bin Laden, and could perhaps direct ground forces to capture him. It could also shoot and kill him.