Well, the response is twofold:
1.) First of all, our [possibly] interventionist policy may have contributed to World War II happening in the first place: We had no real business in World War I, but our leaders basically decided they'd rather have England's side (the Allies) win, so we secretly aided them instead of remaining neutral*. Our meddling resulted in the sinking of the Lusitania. We stayed out of the war at the time and made the Germans swear to stop unrestricted submarine warfare against "passenger ships," but they knew that we were still "up to no good" and still shipping arms to England. Hence, they secretly contacted Mexico and tried to enlist them as their ally to fight the US in the event that we joined the war against them. Then, they resumed submarine warfare. When we found out that they contacted Mexico with that offer, we were "outraged" and joined the war. Had we not joined, the outcome could have been different. Maybe the Germans would have won? Or maybe they still would have lost, but the Treaty of Versailles would not have been as damaging to them? There are a lot of possibilities. However, as things went, the Germans lost the war and the Allies made them pay reparations that devastated their whole country. These reparations are considered by most historians to be one of the main causes of World War II, because Hitler rose to power by playing on the emotions of the impoverished German people.
2.) However, assuming things would have happened the exact same way, Ron Paul's policy is not
entirely noninterventionist: As he has stated before, he thinks that our entrance into World War II was entirely justified, because Germany's pattern of invasion and conquest was becoming a threat to the national security of the United States. Really, this pattern was a threat to England and France first, but they allowed it to continue even while Germany was invading very nearby countries. So: If a country were to invade Mexico or Canada, Ron Paul's otherwise noninterventionist policy would most likely dictate going to war (so long as Congress declared it), because Mexico and Canada are close enough that threats to them are also probably threats to us. Furthermore, if a country was building a dangerous empire on the other side of the world and rapidly conquering other countries (as Germany did), it could similarly be deemed a threat to us, so we'd get involved then, too.
*There's still some controversy over this, but for all intents and purposes, this is the way it went down.
Plus, as someone else stated, it would have helped if people like the Bush family didn't fund Nazi Germany in the first place.
