By The Economist
http://www.economist.com/world/united-states/displaystory.cfm?story_id=16274535

THE Predator is an unmanned aerial vehicle, 36 feet (11 metres) long with a 66-foot wingspan. With no pilot inside there is room for lots of gear: optical sensors, synthetic-aperture radar, forward-looking infra-red. Two people fly each Predator by remote control, steering the bird to investigate disturbances.

In America’s harsh south-west, the Border Patrol monitors signals from hundreds of sensors scattered through the desert. The sensors pick up human activity—migrants being led through the rough terrain, men smuggling sacks of drugs—but also coyotes and strong winds. On a recent night, the sensors were triggered 19 times. Seventeen of the incidents were dismissed as false alarms. For the other two, the Predators were summoned.

“It’s a non-stop game,” says General Michael Kostelnik, the head of the Border Patrol’s air and marine division. As the agency has built up its enforcement capacity around cities and other ports of entry, they have seen some shifts in strategy from the smugglers. The Predators are a key “force multiplier”, especially helpful in rugged, isolated stretches.

Predators already fly over New Mexico and Arizona, and along America’s border with Canada. Since June 1st they have been authorised to fly over El Paso and the Big Bend region of west Texas. And on May 25th Barack Obama announced that he would send 1,200 National Guard troops to the border. These are the most recent moves in the never-ending attempt to secure America’s border with Mexico. The effort has seen the size of the Border Patrol double in the past five years (to some 20,000 agents), and the construction of hundreds of miles of fence.

Not enough, says one lot of critics. National security theatre, says the other lot. Their arguments will influence the coming debate over immigration reform as much as the closely related issue of border security. Data suggests that migration flows have slowed in the past few years, due to the recession and because of expanded enforcement. Deportations have been increasing steadily since 2002. And border security is in some respects improving: drug seizures have, for example, increased.

At the same time Mexico’s drug war continues with unabated ferocity, and the concerns about spillover violence are real. In March two Americans, one of them a consular official, were killed in Ciudad Juárez, just across the border from El Paso. That same month Robert Krentz, an Arizona rancher, was killed while he was outside working. Although the murder is unsolved, the ranch is located in an isolated stretch of the state that is known to be a smuggling corridor.

This has made Arizonans understandably nervy. The state’s strict new immigration law, enacted in April, was presented as a security measure. In signing the bill Jan Brewer, the governor, said that federal inaction and bad policy had “created a dangerous and unacceptable situation,” with cartels operating within the state.

The pitfall, though, is that conflating immigration reform and border security may backfire. Two states over in Texas, Rick Perry—also a law-and-order kind of governor—criticised Arizona’s approach. His argument was that law enforcement should focus on criminal aliens. Efforts to crack down on the larger pool of undocumented immigrants could be a distraction.

Henry Cuellar, a Democratic congressman from Laredo, Texas, says that he would break immigration reform into three component goals: securing the border, creating a guest-worker programme and figuring out what to do about the estimated 12m people who are already in America, undocumented. That last bit, he says, will be the hardest part—and although securing the border needs work, it is unproductive to let the other two goals wait until it has been done.

Unproductive, but perhaps unavoidable. The reality is that Mr Obama’s ability to pursue immigration reform will depend partly on his ability to convince the public, and congressional Republicans, that security will not be sacrificed in the process.