German President Horst Koehler was among the many prominent figures in Budapest Saturday for an official celebration of the 20th anniversary of the day when Austria and Hungary symbolically cut the barbed wire fence that had separated their countries for four decades, according to dpa. "I thank the Hungarian people on behalf of all Germans for the signal of 1989, for their courage and their solidarity with the East German refugees," Koehler said during a speech in the Hungarian parliament building. A letter from Barack Obama was read out at the commemoration, in which the US President spoke of the rarity of dates as significant as this, on which the world "bears witness to such a triumph over adversity". "We salute all those who bravely stood up for change," Obama wrote, according to the local news agency MTI. Among the attendees at the international celebration were the presidents of Austria, Finland, Slovenia and Switzerland, Czech Prime Minister Jan Fischer, and high ranking officials from some 20 other countries. The "signal" President Koehler spoke of was when then Hungarian foreign minister Gyula Horn joined his Austrian counterpart, Alois Mock, in front of the world's media to cut the barbed wire fence near the Hungarian border town of Sopron on June 27, 1989. In fact, Hungary had begun to dismantle its border defences two months earlier. By June 27, there was actually very little barbed wire left to cut. Nevertheless, East Germans watched the event on Western television and rushed to Hungary, their favourite officially approved holiday destination, in the hope of escape. Although they found the Austria-Hungary border was still very much closed and manned by armed guards, East Germans continued to arrive in their thousands until, on September 11, 1989, the Hungarian authorities opened the border completely. Some 12,000 East Germans rushed into Austria then north to be reunited with West German relatives from whom they had been cut off for 40 years. The photo opportunity was a key milestone on the road to the opening of the Berlin wall on November 9, 1989, the fall of Communist dictatorships across Eastern Europe, and the eventual reunification of Germany.