Three of the young Somali-American men who traveled from Minnesota to fight in civil war in Somalia later carried out suicide attacks there.
Major Hasan undoubtedly went into his attack on a military base full of armed U.S. soldiers believing that it would be the last thing he did before he died. (That prediction did not come true. He was wounded in the attack but not killed).
The Al Qaeda recruit Zazi, who plotted to bomb the Manhattan subway in the summer of 2009, planned to die in this attack but was arrested before he could pull it off.
7. Were the brothers really "lone wolves"?
Given all the mayhem the two brothers are allegedly responsible for -- two bombings that caused three deaths and some two hundred injuries at the Boston Marathon as well as the subsequent murder of a policeman at MIT -- did they have some kind of additional help?
According to Boston law enforcement officials, there is no evidence of such help and it's worth recalling that Hasan was entirely a lone wolf who nonetheless managed to kill 13 on a U.S. military base with heavy security.
8. Did the older Tsarnaev radicalize his younger brother?
Perhaps. Where there is some kind of terrorist cell there is sometimes a leader who instigates action. We saw this in the case in Lackawanna, New York where a group of Yemeni-American men who trained with al Qaeda in Afghanistan before 9/11 were radicalized by Kamal Derwish, a Yemeni American who had spent many years living in Saudi Arabia. Derwish encouraged his fellow Yemeni-Americans to travel to Afghanistan for military training.
9. How unusual is it for brothers to carry out terrorist attacks together?
More frequent than you might think. The deadliest terrorist attack in U.S. history on 9/11 involved three pairs of brothers among the 19 hijackers: brothers Waleed and Wail al-Sheri, Hamza and Ahmed al-Ghamdi and Nawaf and Salem al-Hazmi.
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