BARACK Obama has departed from previously accepted policy by declaring the US would not use nuclear weapons against non-nuclear states that adhered to an international treaty agreement - even if they launched attacks using biological or chemical weapons. The President's decision to limit the potential use of US nuclear weapons is included in a revamped strategy to be issued today. Mr Obama said he would make an exception for "outliers like Iran and North Korea" that had violated or renounced the main anti-nuclear proliferation treaty. He also reserved the US right to launch a pre-emptive nuclear strike, steering away from...