Isolationism is a category of foreign policies institutionalized by leaders who asserted that their nations' best interests were best served by keeping the affairs of other countries at a distance.
If the US enters into a treaty with another country or countries and those other countries do not adhere to the terms of the treaty then pulling out of the treaty is not isolationist. It is justice.
LOL.... Justice is anything that a person believes is RIGHT? It's the Eye for an Eye thing.... isn't it?
You guys are funny. In a good way... sorta.