“Prophecy says that once the Pope goes to Moscow, Russia will invade Europe in a devastating war.”
Actually, the words “Pope”, “Moscow”, “Russia”, and “Europe” appear nowhere in the entire Bible. So I think you mean “some interpretations of prophecy say...”, because the prophecy themselves certainly don’t say that.
The prophecy does mention all words explicitly, and states that exactly. Russia will invade Europe and Communism will advance across the entire world, but its triumph will not be final. Afterwards Christians will enter a new age where East and West once again become one unified body.
It comes from Garabandal.