What was one of the primary justifications given by the U.S. for its expansionist policies?

One of the primary justifications given by the U.S. for its expansionist policies was the belief in a civilizing mission to uplift other nations. This idea was rooted in the concept of Manifest Destiny, which suggested that it was the United States' destiny and duty to expand its territory and influence. Proponents of this belief held that American values, democracy, and culture were superior and should be spread to "less developed" nations. This rationale was often used to justify actions in places like the Philippines, Hawaii, and Puerto Rico, where Americans believed they were bringing progress and enlightenment through their governance and way of life.

The emphasis on a civilizing mission played a crucial role in shaping American foreign policy during the late 19th and early 20th centuries, portraying imperialism as a moral obligation rather than mere ambition or conquest. This perspective allowed for widespread public support and justification for expansionist activities, framing them as beneficial not only for the U.S. but also for the societies being affected.