Quoting from a
Salon Magazine article, as allowed by the tenets of
fair use:
Jane's magazine estimates that the Taliban have at least a few functional Stingers, an assessment shared by independent sources, including Andrew Gembara, a former U.S. Army special forces officer who is familiar with Afghanistan. He fears that mujahedin veterans may have already smuggled Stingers -- or old Russian SAMs, which are of limited use against modern military aircraft but deadly against a 747 -- into the United States. "The missile for a SAM is slightly bigger than a baseball bat," he says. "The Stingers are somewhat larger but you could put one in a car trunk or a truck."--from http://www.salon.com/news/feature/2001/09/22/blowback/print.html
Whether any of these missiles actually
do end up being used against aircraft may only be a matter of time--but it is almost certain that in the post-
WTC heightened tension, any aircraft
accident or
mishap will be examined closely for signs of such an attack, and
rumors will fly faster than any guided missile.