Why did U.S. officials support Ngo Dinh Diem's refusal to participate in elections aimed at reuniting Vietnam?

U.S. officials supported Ngo Dinh Diem's refusal to participate in the elections aimed at reuniting Vietnam because they feared that the elections would lead to a victory for the communist North, given the popularity of the communist leader Ho Chi Minh. Diem was seen as a staunch anti-communist ally, and U.S. policymakers believed that a unified Vietnam under communist rule would undermine American interests in the region. Additionally, they viewed the Geneva Accords, which called for the elections, as unfavorable to their strategic goals in Southeast Asia.