Well then, Israel has committed nuclear terrorism two times, thus far, and may be about ready to do so a third time (if they go after Iran). I’m not sure how this “will play” ... considering what Israel has done in a useful way in doing what they have done in the past and may do again in the future.
And ... then again ... perhaps someone else might even decide to go after the USA and call it a nuclear terrorist for bombing Japan!
That would be ex post facto. The United Nations came into existence on October 24, 1945. The bombing of Hiroshima and Nagasaki took place on August 6th and August 9th of that year, respectively.