US-Mexico Border Tunnels Evolve to Defy Security Measures

By Sylvia Longmire
Contributor, In Homeland Security

Where there’s a will, there’s a way, and that saying certainly rings true for resourceful drug smugglers. One of the most effective and difficult to detect methods of moving illegal drugs across the U.S.-Mexico border has been the use of drug tunnels. In recent years, tunnel detection technology has evolved, and Border Patrol agents have focused on leveraging human sources to determine tunnel locations. However, smugglers keep managing to stay one step ahead of law enforcement officers, and tunnel construction methods are evolving to keep them there.

A recent report by KPBS outlined the three different categories of drug tunnels as identified by U.S. Border Patrol: rudimentary (cheaply made and stretch short distances), interconnected (exploit existing municipal infrastructure), and sophisticated (often equipped with lighting, electricity, ventilation, water pumps, railways and more). Of the 197 drug tunnels that have been discovered along the southwest border, one third of them were found in the San Diego sector, as well as roughly half of the tunnels classified as sophisticated.

The Tunnel Rats

Lance Lenoir is captain of Border Patrol’s five-person tunnel entry team, known as the Tunnel Rats. When a tunnel is discovered, agents collect as much information as they can about the tunnel’s construction and contents/evidence before either sealing it or essentially plugging it. Filling a border tunnel with concrete on the U.S. side of the border can cost up to $300,000, so not every tunnel prior to 2007 was filled due to budgetary constraints. Prompted by Senator Dianne Feinstein (D-Calif.), who called the tunnels a “national security risk,” Border Patrol has filled every large tunnel up to the border ever since, according to Department of Homeland Security officials.

However, even a half-filled drug tunnel isn’t a deterrent to the determined. According to the Los Angeles Times, at least six previously discovered border tunnels have been reactivated by drug trafficking groups in recent years. Mexican authorities say they lack the funding to fill them or seal them more securely. Even if they are sealed properly, tunnel makers can just dig a new entry point and connect to the existing infrastructure.

Diggers are also making adjustments to tunnel design in response to increased security measures being implemented on the U.S. side of the border. According to David Shirk, director of the Trans-Border Institute at the University of San Diego, cartels are going as far as consulting with top engineers in Europe to perfect their tunnel architecture. Lenoir told KPBS the sophisticated tunnels centered around San Diego are becoming narrower and harder to detect – ranging anywhere from 36 inches to less than four feet in diameter. Cartels have also gotten better at disguising tunnel entry and exit points, including using elevators hidden under floors.

Surveillance and Vigilance on Tunnels

Despite the increased sophistication of tunnel detection technology, Lenoir said the most reliable method of detection has been “good old-fashioned police work,” with officials pursuing leads from informants who notice suspicious jackhammer sounds, large piles of dirt, or people coming and going at unusual hours. Readings from seismic sensors used for tunnel detection can get thrown off by surface clutter and noise, and there is a lot of cross-border traffic in many border areas like San Diego. Radio and electromagnetic interference is another problem.

As security measures along the U.S.-Mexico border expand, drug smugglers will continue to find ways to work around them. The most likely expansion will be addition border fencing, and smugglers continue to demonstrate proficiency in evading surface barriers.