By Pat Ciarrocchi

PHILADELPHIA (CBS) – Compared to the coordinated internationally-rooted terrorist attack of 9-11, the Boston Marathon bombing — though lethal — was a small scale attack.

Could that be a game changer?

Ed Turzanski, the John Templeton Fellow at the Foreign Policy Research Institute, believes it is.

“This is something we’ve been fearing for a long time… that these attacks would come our way… in a smaller dose, but none the less lethal variety,” said Turzanski.

It was strategic, on Patriot’s Day, at the finish line of the Boston Marathon. Three people were killed, more than 150 wounded.

Turzanski, who is a terrorist expert, calls the nature of this attack, disconcerting.

“Before we thought that the risk was too high to come away with so few casualties,” said Turzanski. “We recognize, with this attack, maybe they’re willing to live with that smaller yield because they’re are more of them coming this way.”

As Turzanski watched the FBI released video of 26-year-old Tamerlan, and 19-year-old Dzhokhar Tsarvneav, carrying large backpacks, walking toward the finish line, the brothers just blended in, how they looked and dressed.

“How they were able to set these bags down and then walk away from them without anyone noticing… that’s the part that’s difficult to understand, ” said Turzanski.

Unless you peel back the layers.  Though the Tzarneav brothers have lived in the United States for nearly a decade, they’re natives of Chechnya, where Islamic insurgency, using bombs and gun battles are part of daily life.

“Chechnya has become an exporter of fighters and there are people there who have taken up Jihad,” said Turzanski.

And that why Turzanski says the FBI will trace their movements to try to shape the story of brothers who became killers.

“The older of the two.. who appears to have been the driving force… was radicalized before coming to the United States and he’s a brother.. he would have tremendous influence over his younger sibling,” said Turzanski.

At this point, the bombers’ motivation isn’t known, nor whether there was a political agenda that had anything to do with ethnicity or religion.

We do know that both young men had choices, and they made them.

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