DAVID GREENE, HOST:
And let's talk about the Boston Marathon as a target. U.S. officials have worried for years that terrorists might go after so-called soft targets, where security is minimal and the opportunity to inflict casualties is great. People gathered in shopping centers, football stadiums, outdoor concerts are all highly vulnerable. Until now, we have largely avoided such attacks.
NPR's Tom Gjelten reports on why.
TOM GJELTEN, BYLINE: Marathons have long been a special concern for police and Homeland Security officials, and the Boston Marathon is the oldest, the most famous and one of the biggest in the world. Boston Police Commissioner Ed Davis, speaking last night, said his department always prepares an elaborate security plan for the marathon. Last year's race, he said, brought a bigger crowd than had been seen previously, so the plan for this year was adjusted accordingly.
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ED DAVIS: And there were more officers assigned to this race than we've ever assigned before. And we were particularly concerned with the finish line this year and assigned more officers down in that area.
GJELTEN: Including undercover officers, plus explosive-sniffing dogs. But no plan, Davis said, could guarantee security.
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DAVIS: This is a soft target. When you have an event like this, you can't lock it down like it's a military operation. It needs to be open to the public. And by the virtue of the type of event this is, it requires that we don't turn these events into a police state.
GJELTEN: So events like the Boston Marathon are inevitably vulnerable, and yet terrorists generally have not hit them. One question is: Who would be interested in attacking a strictly civilian target? There was the bombing at the Summer Olympics in Atlanta in 1996 when two people died. The American man who carried out that attack said he saw the Olympics as a symbol of global socialism.
Other domestic terrorists have targeted symbols of the U.S. government, such as the federal building in Oklahoma City, attacked in 1995. Security officials who have fretted about soft U.S. targets like the finish line at a marathon have more generally feared attacks from al-Qaida-inspired jihadi terrorists. The 2010 magazine article in the Jihadi Magazine "Make a Bomb in the Kitchen of Your Mom" invited small-scale attacks.
But Scott Stewart, a terrorism specialist at the intelligence firm Stratfor, says al-Qaida-inspired terrorists haven't shown much interest in little attacks.
SCOTT STEWART: They seem to want to do something more, something more spectacular, something, you know, along the lines of a 9/11-type attack. And it seems to me that those grandiose thoughts or those grandiose desires just lead them to attempt things that are well beyond their capabilities.
GJELTEN: Rather than settle for a small, soft-target operation with a high chance of success, they try something more ambitious and fail, like the unsuccessful attempt to blow up a commercial airliner on Christmas Day in 2009. Philip Mudd, for many years a counterterrorism specialist at the CIA and then the FBI, reaches a similar conclusion that easy-to-hit soft targets like the Boston Marathon just don't hold that much appeal to al-Qaida types.
He imagines a conversation they might have among themselves.
PHILIP MUDD: If we do something small, the people we're trying to recruit and the people who provide us funding are going to step back and say: Is this it? You set a very high bar on September 11th, and now the bar is killing three people, one of whom was a child, at an event that most people around the world don't even know about, that's what your goal is?
GJELTEN: This idea that al-Qaida-inspired terrorists have generally not been interested in small-scale attacks on soft targets might steer investigators toward the theory that the bombing at the Boston Marathon was the work of a U.S.-focused domestic terrorist. But there is a first time for everything. Mudd, with many terrorism cases under his belt, says investigators at this point can't jump to conclusions.
The first mistake you make in a case like this, he says, is saying: I think I know what's happening here. You can't pre-judge, he says. Let the investigation take you where it takes you. Tom Gjelten, NPR News, Washington. Transcript provided by NPR, Copyright NPR.