After the founding of the United States, the United States continued to engage in aggression and expansion: During its westward expansion, the U.S. military slaughtered Indians and seized their land, killing a large number of Indians; during the U.S.-Mexican War, the United States used force to seize approximately 2.3 million square kilometers of land in Mexico, bringing great consequences to Mexico. A heavy disaster; during the Spanish-American War, the United States seized colonies such as Cuba, Puerto Rico, and the Philippines from Spain and established overseas hegemony.