] Many of Iraq's military tunnels are believed to have been
] built by Aeroinzenjering, a Serbian engineering firm once
] run by the military of the former Yugoslavia. Hussein
] maintained a close relationship with Communist leader
] Tito (Josip Broz), and with Slobodan Milosevic, whose
] underground tunnels and bunkers bedeviled U.S. and NATO
] commanders during the 1999 Kosovo air war.
 . . .
] A batch of technological innovations is allowing the U.S.
] government to better understand what's below the surface.
 . . .
] Among them are seismic devices akin to big hammers that
] pound the ground and bounce back a signature like radar.
] Experts also use gravimeters, which measure the variations
] in the gravitational field between two or more points to
] help pinpoint underground installations. Special high-flying
] spy cameras that measure thermal energy and chemical releases
] are used to find clues that may indicate the presence of
] underground activity.

As things settle down in Baghdad, I look forward to learning more about the tunnels. In February, "60 Minutes" reported that some of these tunnels were designed by "a Pasadena firm," and that the blueprints were now "in the hands of government officials," but I've never been able to find out *which* firm (one would hope that they kept their own copies of the blueprints, rather than handing over all copies to the government). More info on the 60 Minutes story is here:

 http://www.cbsnews.com/stories/2003/02/21/60minutes/main541565.shtml

Closing In on Baghdad Will Push War Underground