In Guatemala, Mann attended the inauguration of President Jacobo Árbenz Guzmán and pronounced him a communist. Although he resisted early overtures by United Fruit representatives to intervene, he opposed Árbenz's land reform law, fearing that Guatemala would provide a test case for other nations. After the CIA-backed military coup in 1954, Mann was recalled from Greece to Guatemala. He established Norman Armour as the US ambassador and sought to bolster the new military government of Castillo Armas. Mann reportedly gained de facto veto power over Guatemalan policy; after Mann had rejected a new oil law, Armas said he would come to "no final decision without consulting with Mr. Mann."