The nation's top nuclear weapons agency announced Tuesday that it's planning to field-test devices that could eventually be used by local agencies around the country to disable a terrorist "dirty bomb" or nuclear weapon in the absence of experts trained to defuse nuclear bombs. The plan is an answer to concerns that, in the event of a terrorist plot on U.S. soil, the Nevada-based Nuclear Emergency Search Team wouldn't be able to get to the scene of an attack soon enough. The team, known as NEST, is the first line of defense against such attacks, which federal authorities say could...