The Bucharest Nine or the Bucharest Format is an organization founded on 4 November 2015 in Bucharest, Romania, at the initiative of the President of Romania Klaus Iohannis and the President of Poland Andrzej Duda during a bilateral meeting between them. Its members are Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania and Slovakia. Its appearance was mainly a result of a perceived aggressive attitude from Russia following the annexation of Crimea from Ukraine and its posterior intervention in eastern Ukraine both in 2014. All members of the B9 were either part of the former Soviet Union (USSR) or members of the defunct Soviet-led Warsaw Pact.