There never was a serious possibility that Germany might attack the United States during World War I. The German Navy was confined to German ports by the British Navy, and British convoys dramatically reduced the number of merchant ships sunk by German submarines. The German Army was stalemated on the Western Front, and over a million German soldiers were engaged on the Eastern Front. German boys and older men were being drafted to fill the trenches. There wasn’t any armed force available for an attack on the United States. Despite the suggestion, in German Foreign Minister Arthur Zimmermann’s inflammatory telegram, about a possible alliance between Germany, Mexico and Japan, America was safe.
Wilson claimed that American national security was linked with the fate of Britain, but because the British Navy had bottled up the German Navy and neutralized German submarines, Germany wasn’t capable of invading Britain. In any case, Britain was struggling to maintain its global empire. The settlement following World War I had the effect of adding more territories to the British Empire. Why should American lives have been lost and American resources spent to expand the British Empire?
Why, for that matter, should the United States have defended the French or the Belgians? They were defending their overseas empires, and both had shown themselves to be brutal colonial rulers. The Belgians were responsible for slavery and mass murder in the Congo – the first modern genocide, involving an estimated 8 million deaths.