My thoughts are that launching a nuclear weapon, even if it detonates inside Ukraine, creates a foreseeable risk of radioactive fallout reaching, at the very least, Poland-a member of NATO. If you engage in conduct which creates a known-and likely-risk of an outcome, even American criminal law would impute intent and form the basis for a prosecution. If you drive your car onto a sidewalk in order to kill person number one, but end up killing persons number one and number two, you are guilty of two counts of murder. And the quantum of proof needed for war wouldn’t be that high. We didn’t have to prosecute and convict bin Ladin in order to go into Afghanistan.