Which statement best describes the united states' changing role in the world during the twentieth century? it changed from a great power into an isolationist nation, much like japan. it was vastly richer, larger, and more powerful than it had been one hundred years before. its losses during the war of 1812 substantially weakened its power for the next hundred years. its strict economic controls resulted in a widespread return to mercantilism. it became a military superpower in the world but lacked a strong economy.