Before the war, the US was doing the exact opposite of defending "free people." The US imposed imperialism in several countries and establishing colonies mainly for economic purposes. Before WWII, the US had meddled into foreign affairs in Haiti, Mexico, Cuba, Hawaii, Puerto Rico, Guam, Filipinos, Japan, China, Colombia, Panama, Nicaragua, Dominican Republic, and Honduras. Although several groups seeking for self-determination were brought aid, after they won, the US imposed control over them soon after. For example, the Cubans won their freedom from Spain, with the aid of US. Despite the victory, the US shortly placed troops in Cuba and set up a military base, investments, and rights of intervention. America also conjured a revolution against Colombia and created the "independent" state of Panama, with the main purpose of controlling the Panama Canal. Not only did the US not fulfill its "promise" of defending "free peoples", the country had also countered revolutions as well. In Nicaragua in 1926, the US sent marines and troops there to stop a revolution taking place for seven years. This shows that not only did the US not guarantee their freedom, but the country had tried to stop people seeking for freedom.
During WWII, the US still had colonies and imposed imperial power throughout the world. Despite its own position, the US proclaimed support for national self-determination and independence. Later on the US expressed and implied that the country would help France restore its government and overseas empire after the war. By helping France keep their imperial power, this did not match up the claim of US as the "defender of the free peoples". The US later on intervened in the Middle East due to the high abundance of oil. The US did match the claim to one of the issues of promising that it would not change the Palestine policy without consulting the Arabs. Despite the match, the amount of intervention in foreign affairs outweighed the idealistic claim.
During the war, Roosevelt stated in the Atlantic Charter that the country "seeks no aggrandizement, territorial or other" and that they respected "the right of all peoples to choose the form of government under which they will live." However, after the war, the rivalry between the US and the Soviet Union was tense. The idea of capitalism vs communism appeared several times in global events and affairs. This caused the Korean War and involved the US into the war, with the belief that they were combating communism. The US also passed the Truman Doctrine, which calls for the US to aid groups seeking for self-determination. It was used to help liberate Greece and Turkey. The liberation of Greece and Turkey matched the US's claim. Shortly after, the US often clashed with the Soviet Union in foreign affairs. For example, in Cuba, the US was backing dictator Fulgencio Batista. The Soviet Union then helped rebel leader Fidel Castro overthrowing Batista. Fidel Castro's rule was favorable and popular, satisfying the Cubans. However, the US intervened by sending in troops to take down Castro. The US's intervention in stopping a favorable rule does not match to its claim of defending "free peoples." America's interference with leaders continued in Iran and Guatemala. Guatemala had a democratically elected leader, but he was kicked out by the US due to its decision to take back land from the United Front. This showed that the US never intended to interfere due to its vision of defending "free peoples".
Overall, the unmatched global events and affairs outweigh the matched actions to the US's claim. Through the economic interests in several countries under the US's imperialism, it shows the purpose of US's intervention in countries were due to economic advantages. In the political interests in combatting communism, especially after World War II, the US only used the claim of defending "free peoples" as excuses to intervene in countries that pose a threat to the US. Which is why America's claim of itself as a "defender of free peoples" does not match the reality in global affairs.