Drug Trafficking

Border tunnels left unfilled on Mexican side pose security risk, officials say

Border tunnels left unfilled on Mexican side pose security risk, officials say

Mexican drug cartels have burrowed dozens of tunnels in the last decade, outfitted them with rail and cart systems to whisk drugs under the U.S. border and, after being discovered by authorities, abandoned them.

But some of the illicit passageways live on.

At least six previously discovered border tunnels have been reactivated by Mexican trafficking groups in recent years, exposing a recurring large-scale smuggling threat, according to U.S. and Mexican law enforcement officials.

The breaches of border defenses, most recently in December, occur because Mexican authorities, unlike those on the American side, do not fill the tunnels with concrete once they have been...

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