The two young brothers suspected of exploding a pair of bombs at the Boston Marathon's finish line and fatally shooting a police officer and wounding another probably acted on their own, a UC San Diego professor said.
The brothers immigrated as children from the war-torn Russian region of Chechnya.
Eli Berman, the research director for International Security Studies at UCSD and a professor in the Department of Economics, said the three hallmarks
of organized terrorism were absent from the Boston Maraton bombings, which killed three and injured scores of others.
The Boston Marathon had no political or religious significance, there was no claim of responsibility afterward, or rumblings picked up in advance by western intelligence sources, said the professor, who lived in Boston for 10 years.
"This looks like an aberration," Berman said. "It's called 'lone wolf' terrorism -- it's not attached to any organization.'"
That type of terrorism is difficult to defend against, especially when carried out by just two people, he said. According to Berman, once recruitment becomes more widespread, the word gets out and law enforcement is able to disrupt the plot.
Berman said the destructive power of the weapons the brothers used was "disturbing." The design of the bombs made the large number of injuries possible, he said.
While Chechnya has suffered two recent civil wars, judging the impact of such violence on the brothers would be speculation, Berman said.
Several friends of 19-year-old suspect Dzhokhar Tsarnaev told CNN that he was "a good guy'' who had a lot of friends, wrestled, and did well in school. However, Tamerlan Tsarnaev had once told a photographer, "I don't have a single American friend, I don't understand them."
The Jamestown Foundation, a Washington, D.C.-based independent, non-partisan research institution that provides information on China, Russia, Eurasia and terrorism, estimates that fewer than 200 Chechen immigrants live in the U.S., about 70 percent of them women, according to
The low number is attributed to American anti-terror policies and protests from Russia when ethnic Chechens try to settle here.
Some bombings and other terrorist attacks in Russia have been blamed on Chechen terrorists.