US foreign policy in the 1920s exhibited a strong tendency toward isolationism. World War I had recently ended, American business interests were booming, and many Americans simply did not want to get involved with the conflicts and difficulties of the rest of the world. That said, though, the US couldn't completely ignore international problems. While it declined membership in organizations like the League of Nations and the World Court, it was heavily involved in sorting out the after effects of World War I, trying prevent another war, and protecting its interests in Latin America.
America's European allies (Great Britain, France, and Italy) ended up deeply in debt to the US after World War I, and they really hoped that the US would cancel those debts. While American officials agreed to forgive part of that over $10 billion loan and charge lower interest rates, they still expected their allies to pay up. Even so, they made that requirement more difficult by raising tariff rates with the Fordney-McCumber Tariff of 1922.
Germany was also in a tight spot after the war, for it owed other countries millions of dollars in reparations that it could not even begin to pay. American businessmen were instrumental in coming up with the Dawes Plan of 1924 and the Young Plan of 1929 that tried to help Germany by spreading out and lowering payments and required reparations.
The US was also interested in trying to prevent another war. It was a signatory of the Five-Power Treaty that limited armament build-up and the Nine-Power Treaty that tried to prevent conflicts in Asia. It also participated in the Kellogg-Briand Peace Pact of 1928 in which fifteen nations attempted to outlaw war.
Americans were, however, quite conscious of potential conflicts within and between nations to their south. Relations between the US and Mexico were strained by Mexican attempts to control national resources. The US also sent troops to Nicaragua, which was torn by civil war. Yet in 1928, the Clark Memorandum firmly announced that the US should limit its interventions in the affairs of other Western Hemisphere countries.