Explanation: Imperialism is a policy of extending a country's power and influence through colonization, use of military force, or other means. In the late 19th to early 20th century, the United States practiced imperialism by annexing territories such as Hawaii and the Philippines, and by extending its influence over other countries through economic and military means. The US justified its imperialism as a way to spread civilization and democracy, but it was often motivated by economic and strategic interests.