There is absolutely nothing wrong with full-body scanners. In fact, the more we innovate and introduce new security technologies, the more we can stay one step ahead of terrorists.

But there are major problems with the way the Department of Homeland Security, through the Transportation Security Administration, is handling security at airports.

Requiring more and more passengers to choose (a) a full-body scan or (b) an aggressive pat-down as part of routine screening (also called primary inspection) sends a message that everyone is a terrorist risk when, in fact, almost everyone is an innocent traveler.

Many Americans have legitimate (and some not-so-legitimate) concerns about full-body scans. As such, robust deployment of full-body scans inevitably has led to more opt-outs, which means more folks are choosing pat-downs. Let's be honest, these pat-downs could make the least modest among us blush. It can’t be very comfortable for the poor TSA officer either.

This is a big reason that the TSA now finds itself in a public relations nightmare. Homeland security should not be the stuff of Saturday Night Live. "Don't Touch My Junk" should not be a national catchphrase. So why is the government making flying more and more ... icky?

Homeland Security Secretary Janet Napolitano says it's all part of a "layered defense" to terrorism. Certainly we need multiple layers of security, as Napolitano suggests, but layered defense shouldn't become code for trying to childproof the country against terrorists. And it need not mean piling up physical security measures and applying them all to everyone robotically.

Airport security depends on much more than equipment and pat-downs. Robust intelligence gathering and information sharing among local, state, federal, and international law officers are vital to an effective defense. They can help inform the choices we make in the physical security process so that very few people need to go through the inconvenience of extensive scrutiny.

Intelligence gathering and sharing pays security dividends beyond our airports, too. Many terrorist targets are on the ground, like Times Square, a D.C. subway station, or a Christmas tree-lighting ceremony. At least 34 terrorist plots have been foiled in the United States since 9/11. Most were not directed at airlines. None was uncovered by a full-body scanner.

One lesson that emerges from all these foiled plots is the need to stop the attempt early, before the terrorist has a chance to put the public in any danger. Hint: If a would-be terrorist is waiting in the TSA screening line with a bomb in his shorts, the public already is in danger and the government already has failed.

This is why Napolitano's defense of the more extensive deployment of full-body scanners is so disconcerting. In fact, she recently announced that Homeland Security may start to deploy full-body scanners on trains, ships, and other mass transit. Such a focus has little to do with preventing terrorism before it starts.

Sure, full-body scanners are a legitimate means of screening passengers who merit additional (secondary) scrutiny. We absolutely need some level of physical security at the airports. But the more resources the administration wastes piling up stuff at TSA screening lines, the fewer resources it can devote to practices we know are successful at stopping terrorism.

Jena McNeill is a senior fellow at The Heritage Foundation.