This pin probably was issued in remembrance of the friendship between Yugoslavia and the CCCP. It was a fragile friendship because Yugoslavia was a rebel state within the Soviet Union. At first in 1945 when Tito became leader of Yugoslavia he was the most trusted man of Stalin but in 1948 they split up because Tito was not willing transfoming Yugoslavia in a satellite state of the Soviets.
Yugoslavie continued being a communist state though. And had relationships with both Soviet Union and western capitalist country’s.
Shown are the flags of the Soviet Union and Yugoslavia above the emblem of Yugoslavia.