The Summit of the Americas (SOA) is an international summit meeting that brings together the leaders of countries in the Organization of American States (OAS). Cuba was expelled from the OAS under pressure from the United States after the Cuban Revolution of 1959. Cuba participated in the 2015 summit in Panama, and sent its foreign minister to the subsequent 2018 summit in Peru. In the early 1990s, the formerly ad hoc summits were institutionalized into a regular "Summit of the Americas" based on the principles of democracy and free trade. The meetings, organized by a number of multilateral bodies led by the OAS, provide an opportunity for discussions about a variety of issues and topics.