It has been tried quite a few times. Inevitably, one side or the other does something mildly antagonistic, the other side retaliates, and they are back at war.

Maybe the answer is to do the opposite? Start arming both sides to the gills? Any nation going through nuclear disarmament drops of the nukes in no man’s land between the two? Make it so if either nation so much as sneezes wrong, not only is the region glass, but humanity ends in a nuclear winter, so every country in the world has a stake in keeping the peace?

/s, but I really don’t have much hope for peace, sadly