Against which country? US or China? A close neighbour or worlwide?

Let's make it two scenarios: 1) Against ANY close neighbour 2) Worldwide The distance matters but the country does not matter - the minimum credible deterrent must be such as to retain the capability of hitting the potential opponent back in a meaningful manner if his country is within range no matter the opponent's power.

Hmm, perhaps a better way to think about it: Assumptions: 1) The country is not popular in the international community as it does not subscribe to international values and norms and does not have ethnically related countries that would overlook that 2) The country has a very strong isolationist streak and wishes to be: LEFT MILITARILY ALONE NO MATTER WHAT IT DOES [b]DOMESTICALLY[/b] (no matter whether it is abuse of human rights, oppression of its own people, or even genocide, or whatever else it chooses regardless of how nasty it is, so long as it is done only in its own territory) - of course, the country knows that a nuclear capability will not prevent it from being hit by non-military means (especially diplomatic and economic sanctions) if its domestic behaviour displeases the international community; Hence, the country wishes to deploy a minimum credible nuclear deterrent to accomplish the above goal, but it does not want to burden itself with much more spending on a nuclear than is necessary to do so.