Most nuclear weapon states, including the United States and Russia, have often declared their commitment to getting rid of nuclear weapons. But no nuclear weapon state will feel ready to abandon its nuclear capabilities unless all other nations do likewise. Nuclear arms are therefore likely to remain in military arsenals for a long time and nuclear weapons will continue to be refurbished. But even if one accepts as inevitable the modernizations of nuclear arsenals, can they be managed in such a way that they don't create obstacles to nuclear arms reductions and to complete disarmament in the long run?
The history of Russia-US arms control negotiations provides many examples of nuclear modernizations that created no obstacles to reductions—and that in fact were conditions for cuts. In particular, the US Senate's approval of New START in 2010 was conditioned on accelerated funding for modernizing the US nuclear weapons complex and ensuring the modernization of delivery systems. The logic in such a calculation is quite clear: Arsenal reductions must not create an appearance of weakened security. If nuclear forces are reduced in numerical terms, the need emerges to enhance the efficiency and survivability of remaining forces.
In any event, history shows that nuclear-armed states continually modernize their nuclear weapons. But the factors motivating modernization, and the relative importance of those factors, have varied. In the Russia-US relationship, modernization has been driven by four factors: first, the emergence of new technologies making nuclear arms more efficient and allowing them to be maintained in safer, more secure ways; second, the development by an adversary of disruptive technologies such as air and missile defenses, antisubmarine warfare, and offensive long-range high-precision arms; third, a desire to broaden the functional capabilities of delivery systems originally designed for nuclear missions exclusively; and fourth, the limited service life of existing systems.
Conditions for the Cold War arms race were created by the first two factors—the emergence of new technologies that made nuclear arms more efficient and, especially, the development of disruptive technologies. Ballistic and cruise missiles as well as supersonic heavy bombers were a response to the development of air defenses, while nuclear-powered submarines and submarine-launched missiles with intercontinental range were a response to the evolution of antisubmarine warfare. The impact of ballistic missile defense during the Cold War is somewhat questionable—the effectiveness of ballistic missile defense technologies was quite limited in those days. Still, one cannot exclude the possibility that the Anti-Ballistic Missile Treaty performed an important function by limiting these technologies. And who knows how different the evolution of strategic arms might have been if the parties had agreed to limit disruptive technologies such as air defenses and antisubmarine warfare? What's certain is that, during the Cold War, the qualitative modernization of nuclear arms proceeded so fast that new systems emerged long before the service lives of older systems were exhausted.
The end of the Cold War brought changes in the balance of factors affecting modernization decisions. Though certain US strategic programs continued in the early 1990s due to inertia (a build-up, for example, in new nuclear-powered ballistic missile submarines), a general understanding was reached in the United States that the nation's nuclear arsenal was too large and had lost much of its value in the new geopolitical environment. The primary motivating factor for US modernization thus became a desire to make strategic delivery systems more "usable." The effort began by equipping heavy bombers with high-precision conventional weapons and converting them for non-nuclear roles. Air- and sea-launched long-range cruise missiles were also equipped with conventional warheads. Another development in this vein was the advent of the Prompt Global Strike program, which began as a plan to replace nuclear warheads on ballistic missiles with conventional warheads.
The United States has been modernizing its delivery systems continuously for two decades. But these delivery systems are approaching the end of their originally planned service lives, and their potential for further modernization is limited. On the other hand, accumulated technology advancements are now spurring the United States to build a new generation of delivery systems.
In Russia, for almost two decades, modernization programs suffered from persistent underfunding. The service lives of missiles inherited from the Soviet Union have been extended by factors of two to three. Indeed, Russia's ambitious programs to deploy new delivery systems—which will absorb the lion's share of a broader rearmament plan that, through 2020, will cost 20 trillion rubles—can be explained first of all by the impossibility of extending indefinitely the service lives of existing weapons. But a second factor has played a role in Russia's decision to develop new delivery systems. Specifically, the threat of US ballistic missile defense deployments in Europe, along with the development of US strategic conventional weapons, have been strong arguments in favor of developing new heavy missile and mobile railway systems. (However, it's unclear how these programs will evolve as Russia's economic situation deteriorates.)
Diverging perceptions. In both the United States and the Soviet Union (and later Russia), nuclear reductions were possible in the late 1980s and early 1990s because both sides realized that their accumulated arsenals were excessively large and the arms race was senseless. Since then, arsenals on both sides have diminished progressively. Modernization programs are unlikely to reverse this trend, despite deterioration in US-Russia relations over the last few years. But the two nations no longer perceive similar incentives where making further cuts is concerned.
In the United States, many people still recognize that the US arsenal is too large. President Obama, for example, announced in a 2013 Berlin speech that he would "seek further negotiated cuts with Russia to move beyond Cold War nuclear postures." This proposal seems to have a strong pragmatic goal—to reduce the costs of future modernizations by cutting excess forces. In Russia, however, a number of current trends don't encourage similar viewpoints. In particular, many Russians perceive the unconstrained development of US ballistic missile defense and precision guided munitions as new threats that require a response. Often, these perceptions are influenced too much by emotion. Nonetheless, Russia's industrial and financial resources are limited. Moscow has no ability to influence the qualitative development of US arms. In such a situation, further US development of missile defense and precision guided munitions makes Russia less interested in pursuing the bilateral negotiation process and more inclined to reduce the transparency of its nuclear arsenal.
In the best-case scenario going forward, US modernization programs will have a minor negative impact on bilateral relations. In the worst case, they will become an additional irritant in an already complex relationship. But it is unlikely that bilateral negotiations toward further cuts can begin unless US-Russia relations improve radically.
Even when prerequisites are met for further dialogue on nuclear arms reductions, ballistic missile defense and conventional strategic arms will remain crucial obstacles. Therefore it's important that the United States limit development of such weapons—or direct their development in such a way that other states won't have cause to worry about the survivability of the smaller nuclear arsenals that would result from agreed arms reductions.