Before World War II, the USA had many imperial actions in parts of the world. It had seized Hawaii, Puerto Rico, Guam, and subjugated the Filipinos; it had "opened" Japan to its trade with gunboats and threats; it had declared an Open Door Policy in China as a means of assuring itself would have opportunities equal to other imperial powers in exploiting China. Not just conducting these actions itself, the United States even helped France from opposing the Haitian revolution for independence and instigated a war with Mexico while taking half of the country. Such actions are completely the opposite of what a "defender of free people"does. The United States of America just wanted to conquer other territories to boost its own economy.
During World War II, the USA became a duplication of a Fascist nation. After the Pear Harbor attack, anti-Japanese-American hysteria spread in the government. Franklin d. Roosevelt signed Executive Order 9066, in February 1942, giving the army the power to arrest every Japanese-American on the West Coast and put them into concentration camp, living under prison conditions. This is not what a defender of free people does because it prevented the Japanese-American from gaining self-determination. It is understandable that the Americans were racist against the Japanese because they were suspicious about how they might be having some sort of conspiracies, so they just decided to arrest the Japanese-Americans as a whole; however, there must have been a better way to just arrest all of them. Arresting the Japanese-Americans and putting them into concentration camps just because they were suspicious and they are a different race is clearing not defending them. The Japanese-Americans were free people, too. And by the definition of the "defender of free people", they deserve self-determination, too.
An event that happened during the post-war period that was a significant evidence of how America was not a defender of free people was that the Cuban revolution. Fidel Castro, who led a rebellion in 1959 to overthrow the unpopular ruler of Cuba, Fulgencio Batista, was supported by the Soviet Union. Batista was a unpopular ruler at that time. In an effort to gather information about Castro's army, Batista's secret police pulled in people for questioning. Many innocent people were tortured by Batista's police, while suspects, including youth, were publicly executed as a warning to others who were considering joining the insurgency. And yet, the United States supported this unfavorable leader by sending troops to overthrow Castro. Same thing for the Korean War. North Korea had support from the USSR, so in order for the US to prevent the spread of Communism, it supported South Korea. Actions like these taken by the US show that the United States never did these out of its interest to defend free people, but to do whatever it took to be against the Soviet Union and stop the spread of Communism.
In conclusion, the United States' view of itself as a "defender of free people" does not match to the reality of its actions in global affairs because the United States intervened in global affairs out of economic interests such as the imperial actions taken to boost its own economy, and political interests such as the actions taken to prevent the spread of Communism and be against the USSR.