I think it is a legend about the Vatican implicated in this. It is virtually impossible to keep an underground church in a totalitarian state. Sooner or later, it gets snitched out: no Vatican needed.
“It is virtually impossible to keep an underground church in a totalitarian state. Sooner or later, it gets snitched out”
It is very difficult to establish to keep an authentic Christian church and congregation in a Communist state. The Russian Orthodox church was never an authentic church. It was an arm of the Communist regime. Its priests and bishops were agents and informers for the Communist regime.
They helped the regime identify the Catholic priests in the former Soviet Union and those priests were arrested and killed. It happened at a time when the Vatican was trying to establish communication with the Russian Orthodox Church.