Answer:
When World War I broke out in Europe, Woodrow Wilson announced
that the United States would stay out of European affairs and
remain neutral. He issued a declaration of US neutrality. At the time, a vast majority of Americans approved of Wilson’s policy of strict U.S. neutrality.The United States joined World War II as a response to the bombing of Pearl Harbor in Hawaii by the Japanese on Dec. 7, 1941. The country had been keeping itself isolated from the global war; however, after the attack, the country declared war on Japan on Dec. 8, 1941.
It probably sped up the defeat of Germany by a few months.
It made sure that France was liberated by the western Allies.
and not "liberated" by the Soviets