Why weren't the rebellions successful over the Soviets?
From 1917 until the 1990s, the various rebellions that erupted
against the Soviet Union's official power-holders almost entirely
failed to succeed for primarily one reason: the superior strength
of Soviet counter-insurgency force -- military-, diplomacy-, and
intelligence-oriented alike. It should be noted that Soviet
authority wielded its strength in a decisive manner to stamp out
rebellions both internal and external -- and from the start of its
history. Its effectiveness may thus be attributed in part to
practical experience.