Most countries with nuclear weapons seem to have built them themselves, possibly with help in the process from other countries, rather than buying a ready-made nuclear weapon off-the-shelf.

Considering that some countries have thousands of nuclear weapons, while others have none, it seems like the marginal cost of production is reasonably small compared to the expense of starting from scratch.

Why do countries typically build their own nuclear weapons rather than buy them?

  • 2
    Because of a thing called 'The Nuclear Non-Proliferation Treaty'? Do you think North Korea should have just ordered some warheads from America? Among the major western powers France has its own but Britain uses a combination of American Trident warheads on its own-built submarines and missileD delivery system. The French position perhaps dates from its separation from NATO in the 1960s, when Charles de Gaulle insisted that France needed a Force de frappe.
    – WS2
    Commented Aug 6, 2016 at 6:24
  • 8
    Nuclear weapons are mostly not for sale. You can't buy something from someone who will not sell to you under any circumstances.
    – cpast
    Commented Aug 6, 2016 at 6:42
  • 4
    I don't understand why this question has three downvotes. It's a completely valid question.
    – Philipp
    Commented Aug 7, 2016 at 1:19

2 Answers 2

  1. Various international treaties often forbid countries from selling ready-made nuclear weapons to other countries. For example, the Nuclear Non-proliferation Treaty reads:

    Each nuclear-weapon State Party to the Treaty undertakes not to transfer to any recipient whatsoever nuclear weapons or other nuclear explosive devices or control over such weapons or explosive devices directly, or indirectly; and not in any way to assist, encourage, or induce any non-nuclear-weapon State to manufacture or otherwise acquire nuclear weapons or other nuclear explosive devices, or control over such weapons or explosive devices.

    But such treaties can often be circumvented by selling dual-use technology which can also be used for civil purposes. A centrifuge can enrich uranium until it's usable in a nuclear reactor or even further to make it usable for warheads. A rocket motor can be used to launch a weather satellite or an ICBM. And where is the harm in sending a scientist to Elbonia and have them teach those backward savages some useful knowledge about physics in the name of science? Like how nuclear fission works and what a critical mass is?

  2. It's a prestige thing. Having nuclear missiles is often considered a demonstration of technological prowess and can be used for propaganda (internally and externally). When a country just bought that prowess, the prestige effect is lessened.
  3. Secrecy. Nuclear programs rely on confidentiality. The less other states know about how many nuclear weapons you have, where they are stationed and what exactly they can and can't do the better. When you buy your nukes, the seller knows exactly how many nukes you have and what they are capable of. They might even be aware of critical flaws in your technology you don't even know about yourself. That information can leak.

There are several reasons:

  • Need for constant service and replacement.
    Nuclear weapons decay. The warhead is actually a constantly-running nuclear reactor. Plutonium-239 decays to Uranium-235, increasing critical mass, therefore the warhead is losing its power. A typical modern warhead is guaranteed to be in service for 30 years. Even a standby warhead is simply hot because of running reaction, so it requires some mechanics serviced/replaced.
  • Need for complex equipment and trained staff. Nuclear weapons are different to the ordinary ones because each item is a sophisticated machine which not only consists of the warhead itself, but also requires a whole set of equipment, infrastructure, and trained personnel.
  • A separate, very important, aspect is means of delivery. Ballistic missiles are essential part of each country's nuclear program; check, for example, Iranian Ballistic Missile Program controversy. Note, it's all about the missiles, not the warheads.
  • One more thing, commercial nuclear power reactors typically produce Plutonium-239. It can be more cost-effective to build one and collect Plutonium from the spent nuclear fuel.
  • Non-Proliferation. When a country is accused of selling nuclear weapons, others can impose sanctions.
  • 2
    "The warhead is actually a constantly-running nuclear reactor." Nope. Not for any definition of "actually". Commented Aug 6, 2016 at 13:45
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    "A typical modern warhead is guaranteed to be in service for 30 years." - conventional weapons also have a limited lifespan, either because they don't work any more, or become obsolete, but countries buy them from other countries.
    – Golden Cuy
    Commented Aug 7, 2016 at 0:31
  • @AndrewGrimm, this is true, but still, this does not deny the need for continuous service. For example, the cost of maintenance the nuclear arsenal of Ukraine (1240 warheads incl. 176 intercontinental missiles) was estimated to $5 billion per year, in prices of 1993. Note that Ukraine did have trained staff, factories, equipment, and infrastructure. For a country that does not have the above, the ownership cost would skyrocket (literally). Commented Aug 7, 2016 at 0:53

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