Answer: The Monroe Doctrine.
The monroe doctrine says that Europeans, and for that matter, all foreign powers, should not interfere in the western hemisphere (north america and south america). This is similar to the threat posed by Cuba, as they were being supported by the USSR (Europe/Asia).
The treaty of Versailles held Germany and Austria responsible for starting the war and require Germany to pay repair reparations severely reduced Germany/Austria military and to give up any territory date on to France and Poland
The United States gained Cuba, Guam, the Philippines, and Puerto Rico.
