Answer:
While avoiding the conflict until 1941, World War II marked a turning point for American isolationism. As Germany and Italy swept through Europe and North Africa, and Japan began taking over Eastern Asia, many Americans started to fear that the Axis powers might invade the Western Hemisphere next. By the end of 1940, American public opinion had started to shift in favor of using U.S. military forces to help defeat the Axis. hope this helps.
League of Nations.
It fell apart because it failed to stop WWII (partially because the US didn't join it), and after WWII, the United Nations was created.
In Puerto Rico it was useful, in Cuba not so much. Cubans perceived the outcome as occupation and didn't want to have United States occupation in their country. Puerto-Ricans had a form of a civilian government with independence and Puerto-rican citizenship but the country belonged to US.
I believe its a sun with a face on it.
