How tunnels are built, used along US-Mexico border
As border security has tightened, drug cartels have turned to tunneling beneath the ground to avoid detection.
Nearly 170 tunnels have been found nationwide since 1990, most along the Arizona and California border with Mexico. The job of searching these networks can be dangerous, so the U.S. Border Patrol is unveiling its latest technology in the underground war — a wireless, camera-equipped robot that can do the job in a fraction of the time. (AP)
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