During the 1954 Guatemalan coup d'état, he was among those influenced by the Central Intelligence Agency's campaign of psychological warfare: he remarked that the rebel forces led by Carlos Castillo Armas were being strengthened by thousands of volunteers, which led to his belief that Árbenz could not hold on to power. Sandoval was a member of a military junta created by Carlos Enrique Díaz de León that was supposed to take over the government should Árbenz fall ill. Sandoval eventually sought asylum in the embassy of El Salvador.