Final answer:
In response to Japan leaving the League of Nations, the United States exhibited shock and dismay but maintained a policy of non-intervention until Japan's attack on Pearl Harbor compelled American entry into World War II. Post-war, the US aided Japan's economic recovery, transforming the relationship into a strategic alliance during the Cold War.
Step-by-step explanation:
How the US Responded to Japan Leaving the League of Nations
The United States responded to Japan's withdrawal from the League of Nations with a mix of shock and dismay, particularly in response to Japan's escalating aggression in Asia. Despite these feelings, the US government did little in terms of direct intervention. The surprising attack on the US naval vessel USS Panay brought the conflicts closer to home, but this did not immediately alter the overall American stance of non-intervention. American sentiment at the time generally favored withdrawal rather than increased military involvement in the region.
After World War II, US relations with Japan shifted remarkably. The United States helped to rebuild Japan's economy and shifted its view of Japan from a threat to an ally against Communist China and the Soviet Union. This laid the groundwork for Japan's economic rise and the formation of a beneficial relationship with the United States.