Since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have occupied a hallowed place in U.S. national security. Indeed, during the dawn of the nuclear era, a whole new academic discipline—strategic studies—sprung up to provide the intellectual foundations for policy makers grappling with these earth-shattering issues. Moreover, while easy (convenient?) to forget today, nuclear weapons were central to America’s strategy for defending Europe from the numerically superior Soviet military.

During the Cold War, much of the debate centered on the U.S.-Soviet nuclear balance. And for good reason; this was both the most likely and most dangerous flashpoint. Since the collapse of the Soviet Union, nuclear weapons have continued to be a major preoccupation of American statesmen. However, instead of being concerned by existing nuclear arsenal, the U.S. foreign-policy establishment has been most consumed by the nuclear weapons “rogue” states and terrorist groups don’t have. Meanwhile, outside of government, the strategic-studies community has been replaced by the arms-control crowd, who pours most of its energies into trying to abolish nuclear weapons instead of trying to minimize the danger of them.

None of these pursuits are unworthy in and of themselves. Nonetheless, they’ve created a vacuum whereby few are talking about (much less solving) the nuclear dangers that actually confront the world today. Unfortunately, these haven’t gone away. With the hope of sparking these necessary conversations, here are the five most dangerous nuclear threats no one is talking about:

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Asian MIRVs

As I discussed last month, the most dangerous nuclear threat the world currently faces is the prospect of China and India acquiring multiple independently targetable reentry vehicles (MIRVs). MIRVs allow ballistic missiles to carry up to ten nuclear warheads each one of which can be aimed at a different target.

As we witnessed during the Cold War, the introduction of MIRVed missiles greatly destabilizes nuclear balances, by making nuclear arsenals more susceptible to being destroyed by an enemy first strike. Compensating for this greater danger requires states to build more nuclear weapons and disperse them to more and more places. This will be especially true for India and China, which have maintained extremely small nuclear arsenals relative to the U.S. and Russia.

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Thus, the most immediate impact of China and India acquiring MIRVs will be that they will have to greatly expand the size of their nuclear arsenal. The impact will not be limited to them, however. For one thing, a rapidly expanding Indian nuclear arsenal will leave Pakistan—which is already terrified that it’s arsenal could be destroyed in a first strike—vulnerable. It is likely to respond by expanding its arsenal as much and as quickly as possible, and ultimately by acquiring its own MIRVed missiles (perhaps with the help of China).

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Similarly, Russia has increasingly relied on its massive nuclear arsenal to “offset” its diminishing conventional military power. As China’s military modernization continues, Moscow will become even more reliant on its nuclear weapons to deter the Chinese. Thus, it is absolutely crucial that Russia maintain a large advantage over China in the nuclear realm. A rapidly expanding Chinese nuclear arsenal would greatly jeopardize that. One day we might look back and assess that China’s MIRVed missiles killed U.S.-Russia arms control.

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Pakistan Tactical Nukes

Contrary to popular belief, Pakistan did acquire nuclear weapons to counter India’s arsenal, but rather to “offset” India’s conventional superiority.

Indeed, the decision to pursue nuclear weapons was made at a January 1972 meeting in Multan in south Punjab, Pakistan. The prior month, Pakistan’s military had been badly humiliated in its war with India, which resulted in East Pakistan becoming the independent state of Bangladesh. This halved Pakistan and, as a result, widened the gap with India in terms of population (from 5:1 in India’s favor to 10:1 in India’s favor) and economic potential. It also shattered the prevailing belief in Pakistan at the time that its military was qualitatively superior to the Indian armed forces, and confirmed (in the minds of many Pakistanis at least) that Delhi was bent on dismantling Pakistan.

As a result, it is not altogether surprising that Pakistan is seeking tactical nuclear weapons to use on the battlefield against India, especially in light of Delhi’s “Cold Start” doctrine. After all, NATO deployed tactical nuclear weapons because it sought to use nuclear weapons to offset the Soviet Union’s conventional superiority.

However, tactical nuclear weapons should be concerning to all, especially when fielded by a country like Pakistan. For one thing, fielding tactical nuclear weapons underscores Pakistan’s willingness to use atomic weapons even to counter non-nuclear threats. Moreover, in order to be effective, Pakistan’s tactical nuclear weapons would have to be kept in a more ready state in order to be usable on short notice. Furthermore, once deployed on the frontlines, the battlefield commanders would likely be granted the authority to use them, raising the danger of a rogue general sparking a nuclear armageddon. Finally, tactical nuclear weapons, especially when deployed, would be more susceptible to theft by any one of the countless terrorist groups that call Pakistan their home.

Usable Nukes

An insane amount of analysis has gone into parsing out how precision-guided munitions and their support systems—achieving much greater accuracy—have impacted conventional warfare. An equally insane amount of apathy has been shown towards how the revolution in accuracy affects nuclear weapons.

Nevertheless, the growing accuracy of modern missiles has the potential to greatly undermine strategic stability. Indeed, Keir Lieber and Daryl Press—who are easily doing some of the best work on existing nuclear weapons—even argue that the revolution in accuracy spells the end of mutual assured destruction (MAD).

MAD, and the related tradition of non-use of nuclear weapons, was underpinned by a couple of important assumptions. First, that states had secure second-strike capabilities that made it impossible for states to destroy an adversary’s nuclear arsenal with a surprise attack. Second, that the destructive power of thermonuclear weapons—and the indiscriminate nature of this destruction—made them abhorrent to use. Related to both of these was the notion that no state could win a thermonuclear conflict between two nuclear powers.

As Lieber and Press have brilliantly documented, the revolution in accuracy threatens to undermine many of these assumptions. To begin with, the incredible accuracy of modern missile systems makes a successful first strike far more plausible. This is especially true against states not named Russia and the United States who have relatively small nuclear arsenals (at least for now).

However, after modeling a prospective first strike against Russia’s strategic forces, Lieber and Press concluded that the U.S. could execute a successful first strike with a high degree of probability against even Moscow’s massive nuclear arsenal. In fact, they claimed that U.S. policy makers had actually constructed America’s strategic forces with the goal of strategic primacy (defined as “the ability to use nuclear weapons to destroy the strategic forces of any other country”) in mind. Furthermore, they later concluded that this effort extended beyond nuclear weapons. As they explained in 2013, “the effort to neutralize adversary strategic forces—that is, achieve strategic primacy—spans nearly every realm of warfare: for example, ballistic missile defense, anti-submarine warfare, intelligence surveillance-and-reconnaissance systems, offensive cyber warfare, conventional precision strike, and long-range precision strike, in addition to nuclear strike capabilities.”

Besides jeopardizing MAD, the growing accuracy of modern missiles also potentially undermines the foundation of the tradition of non-use of nuclear weapons. This tradition was built in no small part on the notion that nuclear weapons were morally abhorrent because their massive destructive power and the corresponding radiological fallout would wipe out populations indiscriminately. However, accuracy is the most important determinate of a nuclear weapon’s lethality (Yield of warhead^2/3/ CEP^2). As one scholar explains: “Making a weapon twice as accurate has the same effect on lethality as making the warhead eight times as powerful. Phrased another way, making the missile twice as precise would only require one-eighth the explosive power to maintain the same lethality.” Furthermore, radiological fallout operates according to Newton’s inverse square law.

All of this is to say that with highly accurate missiles, nuclear weapons become a viable weapon of war. As Lieber and Press put it, “the revolution in accuracy permits planners to target an enemy’s hardened nuclear sites using low-yield weapons, set to detonate as airbursts, thereby vastly reducing fallout and collateral damage.” Indeed, using a Pentagon computer model, experts estimated that a U.S. counterforce strike against China’s ICBM silos using high-yield weapons detonated at ground blast would still kill anywhere between 3-4 million people. Using low-yield weapons and airbursts, this figure drops to as little as 700 fatalities!

China’s Military Modernization

China’s military modernization is hardly a hypothetical nuclear threat. At the very least, as noted above, it will force Russia to become increasingly reliant on its nuclear weapons. This is likely to be true of India as well. Moreover, as Bridge Colby masterfully outlined in the latest issue of The National Interest, the U.S. may find in the not-so-distant future that it, too, must once again turn to nuclear weapons to deter a conventionally superior foe in a distant theater.