The Politburo (political bureau) is the highest ruling body in the USSR. In Soviet politics, there were three competing centers of power: the Communist Party of the Soviet Union (CPSU), the Committee for State Security or KGB, and the Soviet Military. The people of the Soviet Union were excluded from participation in the political process and without political rights.
The CPSU dominated political control, yet could not govern alone. The KGB, described as "the sword and shield of the Party" controlled the apparatus of the state security police and its Corrective Labor Camps, or Gulags, for dissenters and other persons who may have had some difficulty cooperating with the Soviet regime. The Soviet Military, a large force in numbers though not ideologically driven as Party members were, represented the only real threat to Communist domination and control of the Soviet system. Thus KGB also functioned as a counterbalance to keep the the Soviet Military in check. And the mass of Soviet people were excluded from any meaningful role in political affairs.
As Soviet defector Victor Suvorov has described, the Politburo "should not be seen as the summit of the Party, for it represents neutral territory, on which the three forces gather to grapple with one another." Suvorov gives numerous examples throughout Soviet history how this process functioned; for example it was the KGB that liquidated Military leaders in the Great Purges of 1938 at the behest of the Party when their loyalty was in doubt. "Both the Army and the KGB are equally represented in the Politburo. With their agreement, the Party takes the leading role; the Party bosses restrain the others and act as peacemakers in the constant squabbles."
Suvorov said of the role of the Politburo in Soviet society, "In effect it has become a substitute for God."
- Victor Suvorov, Inside the Soviet Army, Macmillan Publishing Co., 1982.