How do you cross a heavily guarded border? By going underneath it.
That's the lesson of the Gaza tunnels, which we explored in January and February . It's the key to undersea drug smuggling and terrorism via submarines . And it's happening along the U.S.-Mexico land border, too. William Booth of the Washington Post , who brought us the latest on drug-running submersibles, has an update from U.S. Border Patrol agents in Arizona:
In the past nine months, they have discovered 16 new tunnels dug by smugglers in Nogales to move drugs, migrants, cash and weapons between Mexico and the United States. The number of tunnels sets a new record. ... The digging has become so extensive beneath Nogales that the southbound traffic lane through the international port of entry collapsed. "Before that, the parking lot at the customs office caved in," Howells said. "They collapse all the time."
The tunnelers pop up all over town. Border Patrol agents report that it is not uncommon to see a manhole cover suddenly lift during rush hour and men run out of the hole. The passageways come up through rental house floors, in abandoned stores and in back yards. Agents have found exits near a taco stand, a Chinese restaurant and the local Burger King. ... The latest tunnel, found two weeks ago, was 83 feet long and had ventilation tubes, wooden beams and plywood ceilings. It was just down the block from the port of entry manned by hundreds of U.S. agents.
As we learned from researching the Gaza tunnels, detection is difficult. Ground-penetrating radar, for instance, was a favorite tool along the Mexican border until tunnelers discovered that it can't see deeper than than one meter in wet dirt or 15 meters (49 feet) in sand, dry soil, or rock, which means you can dig below its range. The tunnels in Nogales seem to be near the surface. But if their numbers are increasing, then probably so are those of the tunnels we can't see.
In a world increasingly saturated by patrols, barriers, and surveillance, you have to remember that space is three-dimensional. You can't spot threats and breaches just by looking around. You have to look up. You have to look down at the ground. And increasingly, you have to look through it.