During the Cold War, the United States became embroiled in the Vietnam War, which was a significant military conflict characterized by complex political dynamics and social upheaval. By the late 1960s, the U.S. escalated its involvement in Vietnam, seeking to stop the spread of communism in Southeast Asia. This decision had profound effects both domestically and abroad. A pivotal moment occurred in 1968 when various events, including the Tet Offensive and widespread protests, led many to question U.S. policy. What was one of the primary reasons for the United States' initial military involvement in Vietnam?