Why do countries turn to isolationism? What was the cause of it?
Isolationism is a category of foreign policies institutionalized by leaders who assert that their nations' best interests are best served by keeping the affairs of other countries at a distance. One possible motivation for limiting international involvement is to avoid being drawn into dangerous and otherwise undesirable conflicts. There may also be a perceived benefit from avoiding international trade agreements or other mutual assistance pacts.
United States in Isolation
Japan in Isolation
Myanmar Isolationism