One hears so much about “wake-up calls” in regard to terrorism.  The attacks of 9/11 were a wake-up call of course, as were the shoe bomber, the underwear bomber, the Times Square bomber, the Fort Hood shooting, the plot against Fort Dix, and any number of other attempted or completed terrorism incidents you could name.  And now we have the Boston Marathon bombings being described as, yes, another wake-up call.

What with all these wake-up calls coming hard and fast, we should expect everyone to be well caffeinated and alert to the danger by now, shouldn’t we?  And yet many of us persist in a kind of blissful torpor, unable or unwilling to recognize the threat in our midst even as our fellow citizens are being incinerated, shot, or blown to bits.

Naïveté and innocence are welcome attributes in a small child, not so in an adult.  But even as the number of casualties in Boston were still being tabulated, even as the smoke was clearing on Boylston Street and the city’s emergency rooms were filling to capacity and beyond, even as the police and FBI were sifting through the evidence left behind on the bloodstained sidewalks, naïveté and innocence were on grand display in the media.  Among the pap churned out in the immediate aftermath of the bombings was the article that famously and laughably typified the head-in-the-sand attitude so prevalent among our sophisticated betters in the press: David Sirota’s piece at Salon.com, “Let’s hope the Boston Marathon bomber is a white American.”

Indeed, it seemed as though no one in the mainstream media dared even suggest the possibility that the bombings had been the work of Muslim jihadists, this despite the near-universal suspicion outside their little bubble that they were.  Well, we were told, it was tax day, and it was mid-April, and it was almost Hitler’s birthday, and on and on and on with the scarcely concealed wishes that the atrocity would turn out to be something other than what it was: the latest on a long list of Islamic terror attacks on American soil.  (And note that the list includes only those incidents in which at least one person was killed; a list of foiled and abortive plots can be found here.)

And if it wasn’t bad enough that the media tried to ignore the most likely explanation for the bombings, even when the suspected perpetrators were in fact identified as Muslims, we were told this was merely a coincidence, that their crimes weren’t necessarily motivated by their religion.  The headline over an article at The Atlantic website neatly distilled this point of view: “The Boston Bombers Were Muslim: So?

Oddly, it is our success in the struggle against terrorism that gave us the false sense of security we enjoyed before April 15 — and which apparently is still enjoyed at Salon  and The Atlantic.  On that list of foiled or abortive terror attacks are 31 attempts at large-scale murder, any of which, had it succeeded, would have shocked us into vigilance the way the Boston bombings now have.  The Times Square bomber was big news for a few days, but the bomb fizzled and so did our interest in the story.  Same for the shoe bomber and the underwear bomber and all the rest.  But along come the brothers Tsarnaev to remind us of what we are up against.

How comforting it must be, in places like Salon and The Atlantic, to be so insulated from the perils of the real world that one can sit at a computer and produce articles in which the reader is asked to join the writer in the delusion that those perils do not exist.  The rest of us are not so blessed, so it behooves us to know our enemy and consider how we might protect ourselves the next time he strikes.

As the Boston bombings demonstrated, the authorities charged with rooting out terrorist plots have to get it right every time; the terrorists have to get it right only once.  Those 31 times we were good (or lucky) may seem an impressive total — and indeed it is — except to those so unfortunate as to be on Boylston Street on April 15.  The ease with which the Tsarnaev brothers carried out their crime proves that we can rely on the national security apparatus only up to a point.  The elder Tsarnaev was on a federal watchlist after being identified by Russian authorities as a follower of radical Islam, but his inclusion on the list resulted in no action.

And how could it?  There are untold thousands of people on such watchlists, and many of them present a more clear and present danger than the Tsarnaev brothers did until the day they carried out their crime.  It takes a minimum of five agents in five cars to conduct even a bare-bones surveillance of a single individual, and twice that many to follow someone who is surveillance-savvy.  There aren’t enough federal agents or police officers in the entire country to adequately monitor everyone about whom some suspicion has been raised.

But there are things that can be done. Chief among them is the monitoring of large public events by federal agents and local police officers trained in the art of identifying the criminal in the crowd.  And it is an art, but one based on science.  In every police department there are officers whose ability to spot a stolen car or an armed gang member seems so uncanny to their peers that it is assumed their success is the result of luck.  Similarly, at every international airport and port of entry there are customs agents whose “hit rates” in interdicting contraband far surpass those of their coworkers.  The successes these men and women have are not the result of luck, but rather of their ability to detect the subtle behavioral cues exhibited by people who drive stolen cars, carry weapons, or attempt to smuggle contraband into the country.

In viewing the photographs and video footage of the Tsarnaev brothers moving through the crowd before planting their bombs, I’m certain they displayed the same sort of behavioral cues that a trained observer would have detected.  For example, their backpacks appeared heavier than those carried by others in the crowd, something that might have attracted the notice of someone trained to spot would-be terrorists.  Also, at times they appeared to be together while at others they seemed to try to distance themselves from each other, a red flag to anyone looking to spot troublemakers.  And in some of the photographs they are looking in a direction different from everyone else nearby, an indication that they were interested in something other than the passing marathoners.  None of these cues, or even all of them taken together, would have justified a warrantless search of the brothers’ backpacks, but they might have attracted the attention of an observant police officer who then could have initiated questioning through a consensual encounter.  And a trained observer can almost always detect attempts at deception with just a few questions, usually within seconds of the first contact.

These techniques can be taught and learned, and they should be.  Vice President Biden may comfort himself by labeling the Tsarnaevs as “knock-off jihadis,” but even a knock-off can be every bit as deadly as the real thing.  Surely there are more Tsarnaevs out there waiting for their moment to strike.  Will it take another wake-up call before we figure out how to stop them?

(Thumbnail on PJM homepage based on a modified Shutterstock.com image.)