You comment is precisely correct. It is the trolley problem writ large. That is part of the reason why there are college courses dedicated to the topic, pages

You comment is precisely correct. It is the trolley problem writ large. That is part of the reason why there are college courses dedicated to the topic, pages and pages of historical analysis of the choices made in situations in the past their their outcomes, analyses of the issues leading up to the "fulcrum point" of the crisis, and daily assessments (guesses) of the mental state of, and the response of, the key players in the situation. That these situations are not popping up every day is a testament to the work of a functional state department and diplomatic corps. And it is why the people in that corps who heard a President extorting a foreign leader by withholding military support in exchange political favors, were so horrified.