To ensure the peaceful development of nations, free from coercion, the United States has taken a leading part in establishing the United Nations. The United Nations is designed to make possible lasting freedom and independence for all its members. We shall not realize our objectives, however, unless we are willing to help free peoples to maintain their free institutions and their national integrity against aggressive movements that seek to impose upon them totalitarian regimes. This is no more than a frank recognition that totalitarian regimes imposed on free peoples, by direct or indirect aggression, undermine the foundations of international peace and hence the security of the United States."
this is just a part of the Truman Doctrine but he speaks about helping other nations from becomeing a communist country and he reminds everyone of how we joined with the united kingdom to help stop the spread of it and he starts out by talking about the European countries who are enslaved or on there way to be a communists country hope this helps :)
