The front is just outside Kabul. From the center of the city, it is easy to spot a series of outposts -- small, mud-walled fortresses -- on the snowy mountaintops that ring the capital. Soviet and Afghan troops man the redoubts around the clock, watching for guerrilla movement in the valleys beyond. As soon as mujahedin activity is spotted, Soviet artillery goes into action, and the boom of outgoing fire echoes through the city.
The defense of Kabul, however, is undergoing its biggest change since the Soviets invaded Afghanistan a decade ago. Having already withdrawn most of its 115,000-strong invasion force,...