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U.S. Border Patrol Agent Ryan Grimm demonstrates how a robot is used to navigate a drainage canal along the border fence during a briefing in Nogales, Ariz., Tuesday, Jan. 14, 2014. With more than 75 underground drug smuggling tunnels found along the border since 2008, mostly in California and Arizona, the Border Patrol is utilizing the wireless, camera-equipped robot, to search underground while keeping agents safer. (AP Photo/Brian Skoloff)

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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