If your son served on the Ohio in 2008 or later then he was telling the truth as the Ohio and three others (the oldest boats) were converted into cruise missile boats.
It was converted in Bremerton and the summer I got to visit my son I was allowed to go into all but the reactor room. It was incredible; you were in the midst of a gigantic machine. Wires, pipes, instruments everywhere. I was awed by it and the realization of just how huge and destructive these weapons really are. It is one thing to theorize about them and another to actually see them.