Assessments Find Threat of Suicide Attacks in U.S.

Government security bulletins says Al Qaeda intent on attacking U.S. targets

''These are new circumstances for us to deal with, and this is an aggressive policy to respond to a narrow set of circumstances,'' Chief Estey said in an interview Thursday. If an officer believes he is confronting a suicide bomber who may be about to explode a bomb, he said, the new guidelines ''call for a head shot, which unfortunately is the securest way of disabling someone who may have a suicide device and may try to detonate it.''

Chief Estey acknowledged that the shooting death last month in a London subway of a Brazilian man, whom the police mistakenly thought was a suicide bomber, underscored the tragic possibilities if the police make the wrong decision.

For an officer to make a spot decision on whether someone is a would-be suicide bomber ''is a real tough question, and there are situations where you're not sure,'' he said. ''But when you're making those decisions on the fly, you have to have the greater public good in mind and try to save other people's lives.''

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