Following the breach of the Berlin Wall and the collapse of the East German Communist regime in 1989, Kohl's handling of the East German issue would become the turning point of his chancellorship. Kohl, like most West Germans, was initially caught unawares when the Socialist Unity Party was toppled in late 1989. Well aware of his constitutional mandate to seek German unity, he immediately moved to make it a reality. Taking advantage of the historic political changes occurring in East Germany, Kohl presented a ten-point plan for "Overcoming of the division of Germany and Europe" without consulting his coalition partner, the FDP, or the Western Allies. In February 1990, he visited the Soviet Union seeking a guarantee from Mikhail Gorbachev that the USSR would allow German reunification to proceed. One month later, the Party of Democratic Socialism – the renamed SED – was roundly defeated by a grand coalition headed by the East German counterpart of Kohl's CDU, which ran on a platform of speedy reunification.