America’s enemies come from within and without. We started the week talking about foreign enemies like North Korea and Iran, but the terror attacks at the Boston Marathon were a forceful reminder that terrorism also occurs from within.

So, I am concluding this week with the question: What is more worrisome to you—an attack from a foreign source or domestic terrorism?

Compare your response to the rest of America: More than six of ten Americans (64%) say that domestic terrorism is a bigger threat than an attack from terrorists outside the United States, according to a poll by Rasmussen Reports.

Yesterday, the FBI released images of two suspects, urging people who might recognize them to come forward. The crudity of the pressure-cooker bombs has led many to conclude that the bombers were acting alone and independently of terrorist organizations. This remains to be seen, of course, but if it proves true, then the Boston bombings would be part of a horrible trend.

Terror attacks by individuals have increased over time in the United States, according to START, the National Consortium for the Study of Terrorism and Responses to Terrorism. This shift began with the Oklahoma City bombing. As START’s report states: In fact, the attack by an individual unaffiliated with a terrorist organization in Oklahoma City reflected a shift in the nature of U.S. terrorist perpetrators in the mid-1990s. … [S]ince 1995, a much higher percentage of terrorist attacks in the United States have been conducted by unaffiliated individuals, rather than by organized groups. In the period 1995 (post-Oklahoma City) through 2007, 43 out of 131 incidents with attributed perpetrators were committed by individuals—33% of all attacks in the United States in this period.

What global fears keep you up at night?

Do you worry about nations like North Korea or Iran?

Is the lone perpetrator the biggest threat of all?

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