HAVANA, June 5, 2016 (Xinhua) -- Presidents and heads of state of the Association of Caribbean States (ACS) pose for group photos during the opening ceremony of a summit of ACS in Havana, capital of Cuba, on June 4, 2016. Presidents and heads of state of the Association of Caribbean States (ACS) met here on Saturday to push up economic and political cooperation in tackling regional challenges. (Xinhua/Liu Bin)