Underground Threat: Tunnels Pose Trouble from Mexico to Middle East

By Ken Stier Saturday, May. 02, 2009

“Since 2001, more than 100 tunnels have been discovered by U.S. law enforcement, compared with just 15 in the 1990s, and the pace is accelerating. Most of those have been uncovered through human intelligence, since there are no currently available technical means to reliably detect tunnels.”

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