 The military force led by Castillo Armas attempted to make forays towards the towns of Zacapa and Puerto Barrios ; however , these were beaten back by the Guatemalan army . The propaganda broadcast by the CIA had far more effect ; it succeeded in leading a Guatemalan pilot to defect , which led to Árbenz grounding the entire air force , fearing its defection . The CIA also used its planes , flown by American pilots , to bomb Guatemalan towns for psychological effect . When the old planes used by the invasion force were found to be inadequate , the CIA persuaded Eisenhower to authorize the use of two additional planes . Guatemala made an appeal to the United Nations , but the US vetoed an investigation into the incident by the Security Council , stating that it was an internal matter in Guatemala . On 25 June , a CIA plane bombed Guatemala City , destroying the government 's main oil reserves . Frightened by this , Árbenz ordered the army to distribute weapons to local peasants and workers . The army refused to do this , instead demanding that Árbenz either resign or come to terms with Castillo Armas . 
