On 1 April 1952, East German leaders met the Soviet leader Joseph Stalin in Moscow; during the discussions, Stalin’s foreign minister Vyacheslav Molotov proposed that the East Germans should “introduce a system of passes for visits of West Berlin residents to the territory of East Berlin [so as to stop] free movement of Western agents” in the GDR. Stalin agreed, calling the situation “intolerable”. He advised the East Germans to build up their border defenses, telling them that “The demarcation line between East and West Germany should be considered a border—and not just any border, but a dangerous one … The Germans will guard the line of defence with their lives.”Consequently, the inner German border between the two German states was closed, and a barbed-wire fence erected. The border between the Western and Eastern sectors of Berlin, however, remained open, although traffic between the Soviet and the Western sectors was somewhat restricted.