During the 1930s, US public opinion as well as several Senators questioned the validity of US involvement in the Great War. The belief became increasingly common that the nation was deceived into taking part in this bloody conflict by Allied propaganda and to serve the interests of profit-thirsty bankers and industrialists. The conclusions of the Nye Committee in 1934, tasked with investigating the excessive profits made by the war armament industry, reinforced the antiwar position of the American people and finalizes the country’s isolationist policy.

As a reaction to Germany’s re-armament, and to prevent any US involvement in a possible European war, the US Congress voted the Neutrality Act, signed by President Franklin D. Roosevelt on August 31, 1935. The Act prohibits trade in military material with warring countries and travel by US nationals on ships belonging to warring countries. It was amended in 1936 to prohibit loans to warring countries, and then in January and March 1937 to include civil wars.

In the beginning of WWII, the possibility that Great Britain could be defeated is real and the growing Nazi threat is a cause for fear. Roosevelt realizes that the Neutrality Act imposes restrictions on possible US actions; amendments will be adopted to diminish the legislation’s scope. Supplying nations at war will be authorized on the “cash and carry” principle (November 1939) and loans of military material will be possible on a land-lease agreement (November 1941).