[dragonwriter]

> It's worth noting that the Soviet equivalent to NATO was the Warsaw Pact, whose largest military operation was invading a member because they wanted to leave.

I don’t think that’s quite accurate (it seems, unless I’m mistaken, to conflate elements of the Soviet invasion of Hungary in 1956 and the Warsaw Pact invasion of Czechoslovakia in 1968); the Hungarian revolutionaries in 1956 declared an exit from the Pact but that invasion was pure USSR, not Warsaw Pact. Czechoslovakia in 1968 had reaffirmed its intent to remain in the Pact and faithful to Marxism-Leninism just prior to the Warsaw Pact invasion.

Nevertheless, that the Soviet Union invaded two Warsaw Pact members over insufficient perceived loyalty to the USSR’s direction seems to underline your general point of the difference between the Warsaw Pact and NATO, notwithstanding any quibbles of the precise details of either invasion.