In the Cold War days, the KGB relied on an extensive network of Communists and leftist fellow travelers for espionage and propaganda. As the motherland of socialism, the USSR could draw on allegiances from foreign leftists too in love with all the infrastructure projects to care about the prisoners building them.
But the easy ideological solidarity was faltering even during the Cold War. The Molotov-Ribbentrop Pact and the temporary anti-war line demanded of Western Communists and fellow travelers put a bigger strain on the relationship than the assorted trials and executions of domestic Communists had. Khrushchev’s exposure of Stalin drove away the Stalinists and left the apologists. The USSR lost its radical edge and those seeking it turned to Communist regimes in Asia and Third World terrorists.