When a country first acquires nuclear weapons it does so out of a very accurate perception that possession of nukes fundamentally changes it relationships with other powers. What nuclear weapons buy for a New Nuclear Power (NNP) is the fact that once the country in question has nuclear weapons, it cannot be beaten. It can be defeated, that is it can be prevented from achieving certain goals or stopped from following certain courses of action, but it cannot be beaten. It will never have enemy tanks moving down the streets of its capital, it will never have its national treasures looted and its citizens forced into servitude. The enemy will be destroyed by nuclear attack first. A potential enemy knows that so will not push the situation to the point where our NNP is on the verge of being beaten. In effect, the effect of acquiring nuclear weapons is that the owning country has set limits on any conflict in which it is involved. This is such an immensely attractive option that states find it irresistible.