Observers estimate that government forces killed or "disappeared" as many as 15,000 civilians in three years of the Mendez presidency. Amnesty International cited estimates that 3,000 to 8,000 peasants were killed by the army and paramilitary organizations in Zacapa and Izabal under Colonel Arana between October 1966 and March 1968. Other estimates put the death toll at 15,000 in Zacapa alone during the Mendez period. The victims included guerrilla sympathizers, peasants, labor union leaders, intellectuals, students, and other vaguely defined "enemies of the government." Some observers referred to the policy of the Guatemalan government as "White Terror" -a term previously used to describe similar periods of anti-communist mass killing in countries such as Taiwan and Spain.