The only other reason that the US should ever intervene is if there is a severe and corrupt government that is controlling/ governing it's people unfairly and that is why I support the US stepping in with North Korea. Also if the US is in any form of possible danger I believe it should be our power and right to step in and change that possible course of events.
But like any important issue there is a very blurry line as to what constitutes the US to help other countries. The US is a powerhouse but we must remember how to use that power to the benefit to all other countries and our own.