Imagine that the United States agreed to stay out of all foreign conflicts and to not declare war unless attacked (like in 1930-1939 until Japan attacked).
NATO would be given over to the European Union. South Korea would have no protection against North Korea and Japan would have no protection against China. Israel would no longer be given millions of dollars a day. Iran would have less opposition to their nuclear program.
There might be plenty of other possible side effects and I would like to hear them.
So. Would an isolationist America be good or bad for the world?