In 1966, Julio César Méndez Montenegro was elected president of Guatemala under the banner "Democratic Opening". Mendez Montenegro was the candidate of the Revolutionary Party, a center-left party that had its origins in the post-Ubico era. During this time rightist paramilitary organizations, such as the "White Hand" (''Mano Blanca''), and the Anticommunist Secret Army (''Ejército Secreto Anticomunista'') were formed. Those groups were the forerunners of the infamous "Death Squads". Military advisers from the United States Army Special Forces (Green Berets) were sent to Guatemala to train these troops and help transform the army into a modern counter-insurgency force, which eventually made it the most sophisticated in Central America.