<em>United States</em>
Explanation:
The League of Nations was formally made after World War I and was made to create peace and wanted to prevent smaller countries from being overrun, this ultimately failed as World War II began.
The United States was never in the League of Nations, as Congress would not allow it. Even so, the League of Nations was started by Woodrow Wilson, who was the United States' President during World War I. Many of the American people also thought it would not be good to get involved in such affairs.
The League of Nations was weak. It took a lot of time to be able to do anything, did not have any real power, and did not have any troops. By the time the League could even do anything, most of the time smaller countries would already be doomed. It ended up getting abolished because many people saw it as essentially useless.
