Here's a scenario a real president could face one day soon:
Mr. President, Russia has amassed troops on the borders of Poland and the Czech Republic. Putin has cut off all diplomatic contact with the U.S. No negotiations are possible. We can send troops to defend our allies. If we do, we're looking at the potential for World War III. If we don't, we will be in violation of our NATO obligations and we risk losing two key allies to Russian occupation.