U.S. Imperialism during the Late 19th Century

During the late 19th and early 20th centuries, the United States adopted a more aggressive foreign policy, often referred to as imperialism. This period saw the U.S. expand its influence into territories such as Hawaii, Puerto Rico, and the Philippines. Various factors motivated this expansion, including economic interests, national pride, and a belief in the superiority of American culture. In this context, which of the following events or actions is most directly associated with the onset of American imperialism?