US authorities consider drug tunnels on the border with Mexico to be one of the main security threats and declare that they are ready to involve technology, people and resources to detect and close them. We are talking about an extensive network of tunnels that criminal groups use primarily to transport drugs, weapons and money from Mexico to the United States.
As El Universal the magazine found out during a trip with US Border Patrol agents, such tunnels are most actively being built in the Tijuana and San Diego areas. Some of them use existing infrastructure, including the Tijuana sewer system and the San Ysidro border crossing area.
The so-called high-tech tunnels pose a particular threat to US authorities. Unlike primitive underground passages, they are equipped with ventilation, electricity and rail systems, which allow for the rapid transport of large consignments of cargo. In June 2026, US authorities discovered a tunnel between Tijuana and San Diego, about 590 meters long and up to 17 meters deep, with reinforced walls, ventilation, electricity and rails. According to the investigation, it was planned to transport large consignments of cocaine through it.
US border guards admit that detecting such structures is extremely difficult: the border passes through an industrial zone with numerous warehouses, intensive transport traffic and a high level of noise. Criminal groups use this infrastructure to hide the construction and operation of underground routes.
According to the Border Patrol, the 100th illegal tunnel was previously discovered in the San Diego area. Official statistics from the US Department of Justice now count 99 underground passages discovered in Southern California since 1993, 28 of which were recognized as complex in structure.
US border guards note that cartels are adapting to increased control not only underground. Service officers are also monitoring the use of drones to monitor patrols and are concerned that criminal groups may try to use them for attacks.
In the San Diego area, US authorities call the main participants in the struggle for territory the Jalisco New Generation Cartel (CJNG), the Sinaloa Cartel and groups associated with the remnants of the Arellano brothers. According to border guards, the confrontation between them poses a threat not only to Mexico, but also to the American side of the border.
At the same time, according to service employees, modern tunnels are mainly used to transport drugs, money and weapons, but not people. For illegal migration, criminals can use more primitive underground passages, as well as sewage infrastructure.
US authorities claim they are trying to stay ahead of cartels, which are constantly changing their methods of operation. In June 2026 alone, an investigation into one of the tunnels led to the indictment of four people and the seizure of more than a ton of cocaine, worth an estimated $45 million.
