In addition to pledging not to attack non-nuclear states with nuclear weapons (see Less Ambiguous), the United States is also modifying its declaratory policy on how it would deal with non-nuclear nations that attack with chemical or biological weapons, Defense Secretary Robert Gates said Tuesday. Such states that resort to CBW “would face the prospect of a devastating conventional military response” (and not a nuclear counterattack), he explained during the press briefing on the Obama Administration’s nuclear posture review. As with the first pledge, this policy revision removes some of the calculated ambiguity from US declaratory policy on the use of nuclear weapons. However, Gates said, the US “reserves the right to make any adjustment to this policy” if troubling events transpire in the evolution and proliferation of biological weapons, since they have such “catastrophic potential.” (NPR full document; caution, large file.) (Transcript of NPR press briefing with Gates)