Final answer:
The lack of U.S. participation in the League of Nations created a power vacuum and increased tensions among nations, leading to the outbreak of World War II.
Step-by-step explanation:
The lack of U.S. participation in the League of Nations had a significant impact. It created a power vacuum that increased tensions among nations. Without the involvement of the United States, the League of Nations lacked the necessary political and military support to effectively enforce its decisions and prevent conflicts. This ultimately weakened the organization and contributed to the outbreak of World War II.
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