In June 1954, Castillo Armas led 480 CIA-trained soldiers into Guatemala, backed by US-supplied aircraft. Despite initial setbacks to the rebel forces, US support for the rebels made the Guatemalan army reluctant to fight, and Árbenz resigned on June 27. A series of military juntas briefly held power during negotiations that ended with Castillo Armas assuming the presidency on July 7. Castillo Armas consolidated his power in an October 1954 election, in which he was the only candidate; the MLN, which he led, was the only party allowed to contest the congressional elections. Árbenz's popular agricultural reform was largely rolled back, with land confiscated from small farmers and returned to large landowners. Castillo Armas cracked down on unions and peasant organizations, arresting and killing thousands. He created a National Committee of Defense Against Communism, which investigated over 70,000 people and added 10 percent of the population to a list of suspected communists.