American populism in its various guises has been distinguished by 3 basic beliefs:
1) Concentrated wealth & power are pernicious; widespread distribution is the proper condition.
2)War & militarism are ruinous to the Republic and to the character (not to mention physical health) of the populace.
3) Ordinary people can be trusted to make their own decisions.
Isolationist indicates those Americans who believe the defense policy of the United States ought to be just that–defense against direct or immediate threats to our territory.
This means in practice, an opposition to:
1) Imperialism (which is to say, we should not have acquired such spoils of the Spanish-American War as Puerto Rico or the Philippines.)
2) Wars or interventions on behalf of internationalist principles (such as WWI which was to ‘make the world safe for democracy’)
at the behest of global political entities (e.g. U.S. participation in United Nations police actions in Somalia, Bosnia & Lebanon.)
3) Institutions or treaties that transfer U.S. sovereignty to international or multi-national bodies (League of Nations, North American Free Trade Agreement and possibly the United Nations.)