The number of mounted warheads is a very important issue, because a nuclear war will take at most half a day. So all the mounted warheads at that point are the

The number of mounted warheads is a very important issue, because a nuclear war will take at most half a day. So all the mounted warheads at that point are the ones that can be used, nothing more. Of course if the war doesn't come as a surprise but with a lot of buildup, then you can remount everything over a few weeks.