Between 1935 and 1937 Congress passed three "Neutrality Acts" that tried to keep the United States out of war, by making it illegal for Americans to sell or transport arms, or other war materials to belligerent nations.
This act allowed aid to Britain and other allies with wartime equipment. U.S. production moved to creating wartime equipment instead of consumer goods.
During World War II, many nations were interested in attaining atomic weapons and other arms. Truman’s decision to use the atomic bomb on Japan ended WWII in Asia.