- It does not, in any way, shape or form, alter either strategy or operations for Country X. Country X does not have to do anything differently. It needs to simply change its official stance. The cost would be almost negligible.
- The benefit to the world community at large seems to be significant. By not declaring their own nuclear capability, Country X's position cannot be used by other countries to justify their own stance. You had cited the example of North Korea in that North Korea used the exception made to India to justify its own program (This information is, I believe, in the public space). If a policy of 'persistent ambiguity' were followed, then other countries could not use the instance of India to justify their own stance. The problem is that while India has had a good record in the matter of nuclear non-proliferation given that it is a democracy and will probably continue to have a good record, other countries may not have well developed institutions that will permit them to be so. Indeed, they may already have intentions to use a nuclear threat against its rivals or even pass on nuclear technologies to whoever is willing to pay (e.g. terrorist organizations).
- A simple decision tree diagram would be sufficient to illustrate the benefits of such a policy. The diagram looks as follows.
Note that having a nuclear weapons arsenal that runs into four digits is a waste for any country. So a cap of 400 is not a major concession to anyone.
Update (Nov 11): Note that there are now only four countries in the world that are non-parties to the treaty. So the old arguments - often rhetorical - no longer apply since the large numbers of non-parties that previously existed no longer exist. The world's non-proliferation committee can now focus on what can be done about just the four (or maybe five or six) that remain.
It hardly needs to be mentioned that it is to the credit of international non-proliferation organizations and peacemakers everywhere that we now live in a world where there are only 4-6 non-parties to a treaty that is expected to be in force indefinitely given that - at the outset - it was only supposed to last 25 years and given that it was expected that as many as 25 countries would eventually acquire nuclear weapons. There is something to be said for peaceful diplomacy.