A drug smuggling “super tunnel” linking Mexico and the United States, shut down on Wednesday, was one of the most sophisticated ever discovered, revealing the increasingly advanced use of technology by Mexican cartels.

More than 500 meters long, and linking Tijuana with the Californian city of San Diego, the tunnel was equipped with a railway line, electricity and ventilation, reported the BBC.

US officials said the construction of such a tunnel required architects, engineers and laborers and could have cost more than $1 million, meaning only well-financed cartels could build them, reported the New York Times. It was “the largest, most sophisticated tunnel uncovered along the southern border in two years,” said US Immigrations and Customs Enforcement (ICE). US Attorney Laura Duffy said it had been built by the Sinaloa Cartel, reported Proceso.

It had taken about a year to build, but was shut down before it went into operation, following three weeks of surveillance, reported the New York Times. Eight tons of marijuana and 325 pounds of cocaine — valued at nearly $12 million — were seized, and three people were arrested as part of the operation, reported ICE. 

InSight Crime Analysis

Illicit tunnels running under the US border from Mexico have been used by criminal organizations for years, with more than 150 discovered between 1990 and 2011. In recent years they have increased significantly in their sophistication, with the first so-called “super tunnel” equipped with light, rail and ventilation discovered in 2010. The construction of illegal tunnels increased by 80 percent between 2008 and 2012, according to US authorities. Sinaloa Cartel leader Joaquin “El Chapo” Guzman is alleged to have developed a particular expertise in the method.

SEE ALSO: Coverage of Sinaloa Cartel

San Diego Special Agent William Sherman blamed “desperation” for the fact cartels were using different types of technology to move cocaine, but innovation would be a more accurate word. The big criminal organizations have the money and man power to invest in researching and creating ever more advanced drug smuggling methods, reflected in the use of ultra-light aircraft and increasingly sophisticated narco-submarines.

Tunnels have been used not just to transport drugs but also to funnel illegal migrants, arms and contraband into the United States.