The correct option is: "The United States had reverted to a policy of isolationism, and therefore remained neutral."
Isolationism is a doctrine practiced by the United States during a large part of its history with the objective of not intervening in external affairs that did not pose a real threat to their country.
The beginning of the twentieth century brought with it problems that occurred in Europe and the Pacific, and this would end in large part with the isolationist feelings of the United States. The annexation of the Philippine Islands during the Hispano-American War of 1898 displaced US interests to the western Pacific Ocean, at the gates of Japan. USA UU he did not know how to perceive the threats against his position of neutrality. This caused the submarine war of Germany during the First World War, whose objective was to avoid the arrival of supplies towards the British Empire. When the war ended, EE. UU he forgot his new alliances; both the Treaty of Versailles and the League of Nations found little support from Congress.
The interwar period caused a resurgence of isolationism in the United States. After the war broke out in Europe, Americans like Charles Lindbergh, Gerald P. Nye and Rush D. Holt advocated American isolationism.
