Apart from the European Union, Poland has been a member of NATO since 1999, the UN, the World Trade Organization, the Organisation for Economic Co-operation and Development (OECD) since 1996, European Economic Area, International Energy Agency, Council of Europe, Organization for Security and Co-operation in Europe, International Atomic Energy Agency, European Space Agency, G6, Council of the Baltic Sea States, Visegrád Group, Weimar Triangle, Schengen Agreement, Lublin Triangle and Bucharest Nine.