In 1954 Guatemala's democratically elected President Jacobo Árbenz was overthrown by a U.S.backed right-wing military dictator, Carlos Castillo Armas, in a military coup d'état. The 36 year Guatemalan civil war began in the early 1960s with a military rebellion by left-wing insurgency groups against the new regime. In response, the Guatemalan government employed counter-insurgency tactics, and state-based violence and terror began to escalate. The conflict intensified in the 1970s and saw the height of its destruction and casualties in the 1979 - 1984 period. Guatemala's civil war concluded with the 1996 Oslo Agreement which declared a formal ceasefire between the Guatemalan government and the Guatemalan National Revolutionary Unity (Unidad Revolucionaria Nacional Guatemalteca, URNG) forces.