Sorry, but I just can’t outdo Wired’s headline on this one: Pentagon Scientists Target Iran’s Nuclear Molemen:
Iran’s president, Mahmoud Ahmadinejad, apparently takes a personal and close interest in tunnels — he’s a founder member of the Iranian Tunneling Association. Many of those facilities were built as underground shelters in the aftermath of the 1987 “War of the Cities,” when Iraq and Iran exchanged bombardments of Scud missiles.
There are hundreds of miles of such tunnels, created by giant boring machines. The underground locations provide defense and concealment; there is no telling what is a nuclear facility and what is an empty storage space. And even if the entrance is visible, the extent and layout are unknown, making targeting difficult. Even if the site is attacked, the thickness of mountain rock makes them invulnerable to ordinary bombing.
That’s why the U.S. Air Force is rushing the Massive Ordnance Penetrator (pictured) into production. The MOP can punch through sixty feet of concrete; but this is the very bluntest of instruments for the job. There is more subtle technology to seek out and destroy such facilities.
Pentagon mad science division Darpa has an array of research projects devoted to Underground Facility Detection & Characterization.