HAVANA, June 23, 2016 (Xinhua) -- Image taken on June 23, 2016 provided by the Colombian Presidency of United Nations Secretary-General Ban Ki-moon (L) shaking hands with Colombian President, Juan Manuel Santos, prior to the signing ceremony of a historic ceasefire agreement between the Colombian government and the Revolutionary Armed Forces of Colombia (FARC), in Havana, capital of Cuba, on June 23, 2016. (Xinhua/Colombian Presidency)