The idea of a just war recognizes the legitimacy of using military force to respond to injustice when ordinary political means aren't available or effective. (firstthings.com)
However article 9 of the Japanese constitution prohibits Japan from using military force against another state for any reason, except in self defence. (politics.stackexchange.com)
That was a milestone in its decades - long drive to pose an atomic threat to its American adversary that Trump has vowed to prevent, using military force if necessary. (businessinsider.com)