After its formation in 1949 with twelve founding members, NATO grew by including Greece and Turkey in 1952 and West Germany in 1955, and then later Spain in 1982. After the Cold War ended, and Germany reunited in 1990, there was a debate in NATO about continued expansion eastward. In 1999, Poland, Hungary, and the Czech Republic joined NATO, amid much debate within the organization and Russian opposition. Another expansion came with the accession of seven Central and Eastern European countries: Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia. These nations were first invited to start talks of membership during the 2002 Prague summit, and joined NATO shortly before the 2004 Istanbul summit. Albania and Croatia joined on 1 April 2009, prior to the 2009 Strasbourg–Kehl summit. The most recent member states to be added to NATO are Montenegro on 5 June 2017 and North Macedonia on 27 March 2020.