27 years after the collapse of the Soviet Union, nuclear weapons are still the ultimate armament – their destructive power has no equal. The end of the Cold War seemingly reduced the importance of nuclear weapons. Without the specter of totalitarian communism, there was no great existential threat for the Western powers to deter with nuclear weapons. A world without nuclear weapons, or the “global zero,” to some seemed within reach.
While global zero is a goal worth striving for, nuclear weapons will only be abolished when they have been supplanted or made irrelevant by the next super weapon system. With the ability to level cities or military installations, nuclear weapons are the most powerful deterrent – the ultimate guarantor of security. In the meantime, the five official nuclear powers, as defined by Article IX of the Nuclear Nonproliferation Treaty (NPT), must do everything they can to control the proliferation of these weapons. Increased proliferation increases the likelihood of a nuclear weapon used in anger. As such, additional controls on nuclear power plants and fissile materials must be developed in order to prevent new states from developing weapons. In conjunction, a new wave of arms control agreements is needed to build trust between the U.S. and Russia, the largest weapons holders.
When understanding a state’s desire to acquire nuclear weapons, one must ask, “What threat, real or perceived, needs to be deterred?” All states seek their own security. If the enemy has some, then one must get nuclear weapons as well, or else risk a major security threat. This is especially true when the enemy has overwhelming conventional military superiority and has shown that it will use it. Alternatively, states can ally with a larger state possessing nuclear weapons to seek shelter under its umbrella.
Despite their allure, the world has not gone proliferation-happy, as President Kennedy once predicted could happen. This is largely due to arms control agreements and controls on nuclear power technology. The NPT has so far been the most successful at preventing horizontal proliferation (more states getting nuclear weapons). When it comes to vertical proliferation (states stockpiling nuclear weapons), bilateral agreements with strong verification regimes have proven to be effective. The Strategic Arms Limitation Talks (SALT) and Strategic Arms Reduction Treaties (START) between the United States and the former Soviet Union are a prime example of bilateral arms control.
Strict controls on nuclear power and fuel enrichment technologies can help control nuclear weapons proliferation. The same base technology underpins both nuclear weapons production and nuclear power generation. Low enriched uranium powers the majority of nuclear reactor designs. Nuclear weapons need either highly enriched uranium or plutonium. Reprocessing spent reactor fuel creates plutonium, while the same techniques to enrich reactor fuel can also enrich uranium to weapons-grade status. This is the crux of the current crisis with Iran – Tehran believes that the NPT grants Iran an “inalienable right to enrich,” while Washington and the U.N. Security Council believe otherwise.
Article IV of the NPT grants non-weapons states the right to access nuclear power; it does not explicitly mention enrichment. The key words are “for peaceful purposes.” Rigorous, multi-national inspections are necessary to ensure that uranium enrichment past the 20% threshold, and that plutonium acquired during reprocessing is not diverted towards weapons production. The International Atomic Energy Agency (IAEA) Additional Protocol inspections are one way to ensure that nuclear energy programs remain “for peaceful purposes.” Controlling the nuclear fuel itself is another way. In this vein, the Nuclear Suppliers Group (NSG) was founded to promote the verified peaceful use of nuclear power technology through promoting responsible export controls. An example of a comprehensive agreement that includes both inspections and tight control over the nuclear fuel cycle is the “gold standard” Section 123 agreement between the United States and the United Arab Emirates.
and other agreements show that it is possible to control the spread of nuclear
weapons. Sufficiently advanced states will have the latent
capability to go nuclear should they need to;
the technology and knowledge cannot be unlearned. As such, verified reduction
and rigorous export controls are the only ways to ensure that nuclear weapons
do not proliferate, while getting the global number of warheads and weapons
states down to a more manageable level. This is the most practical and
realistic way to prevent nuclear Ragnarok; that is, until nuclear weapons are
made irrelevant and a global zero can be achieved.
 Low (LEU) vs. high (HEU) enrichment refers to the ratio of U-235 to U-238. Typically, LEU for reactors is 3% – 5% U-235. HEU, also known as weapons-grade uranium, is ideally around 95% U-235.
 Past 20% enrichment, uranium becomes significantly easier to enrich.