All wars end Martlet.
The nation-state that you nuke today would have been be your ally tommorow, thats the lesson of history. You utterly destroy nations you are at war with at your peril. The reasons should be obvious enough.
Wars are fought to decide political and economic issues that were not able to be decided peacefully, they are not intended (at least not on the modern world) to completely destroy your enemy, their land, and all their people. If that was the case, the USN would have fired enough Tridents to make Iraq a flat, glass plateau, but they didn't do that. Ask why. There is a reason that despite the proliferation of nuclear weapons since 1945 nobody has used them, because in the end, they go against the long term aims of the user.