The three men briefly running the Soviet Union after Stalin’s death in March 1953 – Khrushchev, Bulganin and Mikoyan – arrive in Sofia in June 1955. A day earlier they had been in Belgrade, trying to heal the rift with Yugoslavia going back to 1948.
In Belgrade Nikita Khrushchev apologised for the excesses of Stalinism without blaming Stalin for them. He appealed to Yugoslavia to re-join the Communist family of nations and cited Lavrentiy Beria rather than Stalin as the instigator of the Soviet-Yugoslav split. Tito made no response and the assembled crowd did not applaud Khrushchev.
No such thing in Sofia. Since May 1955 Bulgaria has been a member of the Warsaw Pact. Quickly losing his authority, 'Bulgaria’s Stalin' Vulko Chervenkov used the visit to demonstrate loyalty towards Moscow and stayed in power for another year till April 1956. His successor Todor Zhivkov had become the head of Bulgaria’s Communists the previous year, clearly waiting for his instructions from Moscow.