A commonly held theory and an often-used argument in favour of the possession of nuclear weapons is that it deters foreign states from military threats against vital interests. For example, see deterrence theory on Wikipedia, which has plenty of references to further sources. As a more specific example, UK government policy states:

UK nuclear deterrence policy consists of 5 main principles:

preventing attack - the UK’s nuclear weapons are not designed for military use during conflict but instead to deter and prevent nuclear blackmail and acts of aggression against our vital interests that cannot be countered by other means

which means that the UK government expects that they do have a deterrent effect.

Is there any quantitative evidence that a nuclear capability deters foreign states from threatening vital interests?

Answers should refer to studies that:

  • Quantitatively compare military aggression (threats or actual violence) to vital interests of nuclear vs. non-nuclear states
  • Quantitatively compare military aggression (threats or actual violence) to vital interests of states before or after they became nuclear powers.

Vital interests would be interests that threaten the functioning of a state. For example, the government would be a vital interest. A vital interest is not a small outlying territory, such as the UK's Falkland Islands.

The Wikipedia list of nuclear states includes major military powers such as the USA, China, Russia, but also lesser powers such as India, Pakistan, and North Korea. Other major powers, such as Germany and Japan, do not have (their own) nuclear weapons.

  • This question was inspired by this question on History.SE.
    – gerrit
    Jun 20 '14 at 15:41
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    People have been arguing about this for awhile, I doubt we are going to get a conclusive answer.
    – rjzii
    Jun 20 '14 at 15:42
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    Is the question whether the purpose is to deter attack, or whether the effect is to deter attack? Whether it has been a factor in deterring any specific attack in the past? Whether it deters a specific type of attack (e.g. nuclear attack but not a terrorist attack)? IMO the question isn't precise because it doesn't identify a specific, published "claim" that it's skeptical of. The quoted claim is about policy and about what the weapons are "designed" to do (not a claim about whether they actually do that).
    – ChrisW
    Jun 20 '14 at 15:47
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    I think you need to be still more specific. Nuclear weapons are not intended to deter all threats, as the UK statement says. Jun 20 '14 at 18:09
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    Producing such data would merely show correlation (or the lack of it), not causation. If nuclear weapons are adopted by growing major powers, aggressive countries or countries predicting future aggression against themselves, we can't conclude that any increase in threats means nuclear weapons were not deterrents.
    – Oddthinking
    Jun 21 '14 at 5:07

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