The Quartet on the Middle East, sometimes called the Diplomatic Quartet or Madrid Quartet or simply the Quartet, is a foursome of nations and international and supranational entities involved in mediating the peace process in the Israeli-Palestinian conflict. The Quartet are the United States, Russia, the European Union, and the United Nations. The group was established in Madrid in 2002, as a result of the escalating conflict in the Middle East by the Spanish Prime Minister Aznar. Tony Blair is the Quartet's current Special Envoy.