Mexican cartels have radio system to warn of attacks

AP/Houston Chronicle:

When convoys of soldiers or federal police move through the scrubland of northern Mexico, the Zetas drug cartel knows they are coming.

The alert goes out from a taxi driver or a street vendor, equipped with a high-end handheld radio and paid to work as a lookout known as a "halcon," or hawk.

The radio signal travels deep into the arid countryside, hours by foot from the nearest road. There, the 8-foot-tall (2-meter-tall) dark-green branches of the rockrose bush conceal a radio tower painted to match. A cable buried in the dirt draws power from a solar panel. A signal-boosting repeater relays the message along a network of powerful antennas and other repeaters that stretch hundreds of miles (kilometers) across Mexico, a shadow communications system allowing the cartel to coordinate drug deliveries, kidnapping, extortion and other crimes with the immediacy and precision of a modern military or law-enforcement agency.

The Mexican army and marines have begun attacking the system, seizing hundreds of pieces of communications equipment in at least three operations since September that offer a firsthand look at a surprisingly far-ranging and sophisticated infrastructure.

Current and former U.S. law-enforcement officials say the equipment, ranging from professional-grade towers to handheld radios, was part of a single network that until recently extended from the U.S. border down eastern Mexico's Gulf coast and into Guatemala.

The network allowed Zetas operatives to conduct encrypted conversations without depending on the official cellphone network, which is relatively easy for authorities to tap into, and in many cases does not reach deep into the Mexican countryside.

"They're doing what any sensible military unit would do," said Robert Killebrew, a retired U.S. Army colonel who has studied the Mexican drug cartels for the Center for a New American Security, a Washington think tank. "They're branching out into as many forms of communications as possible."

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I am surprised US signal intelligence has not tapped into the system before now.  It would seem an obvious way of keeping up with the cartel and their informers.  Once they are aware of the operation, they should be able to trace the various signals and run down the operators.