Most Westerners called the Western sectors "Berlin" unless further distinction was necessary. The West German Federal government officially called West Berlin "Berlin (West)", although it also used the hyphenated "West-Berlin", whereas the East German government commonly referred to it as "Westberlin". Starting from 31 May 1961, East Berlin was officially called Berlin, Hauptstadt der DDR (Berlin, Capital of the GDR), replacing the formerly used term Demokratisches Berlin, or simply "Berlin", by East Germany, and "Berlin (Ost)" by the West German Federal government. Other names used by West German media included "Ost-Berlin", "Ostberlin", or "Ostsektor". These different naming conventions for the divided parts of Berlin, when followed by individuals, governments, or media, commonly indicated their political leanings, with the centre-right Frankfurter Allgemeine Zeitung using "Ost-Berlin" and the centre-left Süddeutsche Zeitung using "Ostberlin". Period following the building of the Berlin Wall After the Berlin Wall was constructed in 1961, West German Chancellor Konrad Adenauer suggested to U.S. President John F. Kennedy that the United States propose a swap of West Berlin with Thuringia and parts of Saxony and Mecklenburg; the city's population would have been relocated to West Germany. Adenauer did not believe that the Soviets would accept the offer because East Germany would lose important industry, but hoped that making the proposal would reduce tensions between the western and eastern blocs, and perhaps hurt relations between the USSR and East Germany if they disagreed on accepting the offer. While the Kennedy administration seriously considered the idea, it did not make the proposal to the Soviet Union. NATO also took an increased interest in the specific issue related to West Berlin, and drafted plans to ensure to defend the city against an eventual attack from the East. A tripartite planning group known as LIVE OAK, working together with NATO, was entrusted with potential military responses to any crisis. On 26 June 1963, President Kennedy visited West Berlin. On his triumphant tour, cheered by hundred of thousands of West Berliners in the streets, he stopped at the Congress Hall, near the Brandenburg Gate, and at Checkpoint Charlie, before delivering at West Berlin's city hall a speech, which became famous for its phrase "Ich bin ein Berliner" and a hallmark of America's solidarity with the city. The Four Power Agreement on Berlin (September 1971) and the Transit Agreement (May 1972) helped to significantly ease tensions over the status of West Berlin. While many restrictions