What event was triggered by the sinking of the USS Maine?

The sinking of the USS Maine in Havana Harbor in February 1898 was a pivotal event that directly led to the outbreak of the Spanish-American War. The explosion of the Maine resulted in the loss of American lives and was blamed on Spain, stoking public outrage and a demand for military intervention. The incident served as a catalyst for the United States to declare war against Spain, driven by a combination of factors including imperial ambitions, humanitarian concerns over Spanish colonial rule in Cuba, and the influence of media sensationalism at the time, known as "yellow journalism." This conflict marked a significant shift in United States foreign policy, as it transitioned from a primarily isolationist stance to one of active engagement in international affairs, ultimately leading to the U.S. acquiring territories such as Puerto Rico, Guam, and the Philippines.

The other options do not relate directly to the events surrounding the sinking of the USS Maine. World War I, the Vietnam War, and the War of 1812 occurred under different circumstances and are not connected to the late 19th-century conflict between the United States and Spain.