Why did the Cuban soldiers come marching into the hospital, where Hymen Roth was being treated, and immediately pull out a gun and shoot Michael's body guard (who was in the process of smothering Roth?)
I believe it was Fredo that tipped off the Cuban soldiers. When Fredo is scurrying off and Michael asks where he's going Fredo says, "I gotta get a real drink." And Michael gives him a suspicious look. I believe that suspicion was justified. A "real drink"? Sounds like a lame excuse to me.
There's no other way the soldiers would march in there unannounced, for no reason.
