The main way in which the principles of humanism and the Protestant reformation were similar is that they both start putting emphasis on the individual, as opposed to a divine group.
At this time colonies were viewed as a major factor in determining a nations power internationally and also an engine for economic growth in a mercantilist system. Therefore, arguments in favor of U.S. Imperialism would have been fueled by the power struggle with European nations to exert global influence and dominance. Another major factor that individuals would have argued for was that colonies would have provided new markets and sources for raw materials for the growing US economy. In the end the U.S. did not become a major imperial power which most likely served the nation's power and reputation in the long run.
Some would argue the Soviet Union, while others say the US. It depends how you look at the question. There are certain things that prove it was the fault of one while some prove it was the fault of another.
