This is a very good read on the state of the art when it comes to submarine-launched missile accuracy, which are presently inertially guided with a stellar update during flight.
https://thebulletin.org/2017/03/how-us-nuclear-force-moderni...
https://thebulletin.org/2017/03/how-us-nuclear-force-moderni...
So you could say the use would be increased certainty your enemies command and control and other bunkers would be destroyed increasing the odds of “winning” whatever happens afterwards.