How did the expansion of the United States affect it's foreign policy?

The expansion of the United States, particularly during the 19th century, significantly shaped its foreign policy by promoting a belief in Manifest Destiny, which justified territorial growth and the spread of democracy. This led to conflicts with other nations, such as the Mexican-American War, and increased tensions with Native American tribes. As the U.S. expanded, it adopted a more assertive stance in international affairs, ultimately paving the way for interventions in the Western Hemisphere and the establishment of the Monroe Doctrine, which aimed to deter European colonialism in the Americas. This expansionist mindset laid the groundwork for America's emergence as a global power in the 20th century.