Cooling towers from the Limerick Generating Station, a nuclear power plant in Pottstown, Pa., sit near a neighborhood. Environmentalists agree that in light of Japan's nuclear crisis, the U.S. should examine existing nuclear plants for safety risks.
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President Obama displays his Nobel Peace Prize during a ceremony in Oslo in December 2009. During his acceptance speech, the president discussed the concept of a "just war," saying: "There will be times when nations — acting individually or in concert — will find the use of force not only necessary but morally justified."