Nuclear Stability in the 21st Century

The beginning of the nuclear age in 1945 generated two conflicting emotions among scientists, superbly captured in the film “Oppenheimer.” One was a sense of achievement at unlocking the mysteries of the universe, and the other was apprehension at having created a bomb so destructive that it could destroy humanity.

Since 1949, when Soviet Union exploded its device, casting a nuclear shadow on the bipolar world, this dilemma has been at the heart of “nuclear deterrence.”

For nuclear deterrence to work, the threat of nuclear use had to be credible, while ensuring that these weapons should never actually be used. Two schools of deterrence theory soon emerged. One was led by Bernard Brodie, who was of the view that deterrence is automatic and ensured through retaliation because the one who initiates the nuclear attack cannot be certain that the adversary’s entire nuclear arsenal has been eliminated. In a 1946 essay, Brodie made the famous statement: “Thus far the chief purpose of our military establishment has been to win wars. From now on, its chief purpose must be to avert them. It can have almost no other purpose.”

The other school was led by Albert Wohlstetter, who believed that credible deterrence needed assured second-strike capability and therefore large and survivable arsenals to prevent a nuclear Pearl Harbor. For Brodie, just the risk of retaliation was an adequate deterrent; for Wohlstetter, it was the certainty of retaliation with large numbers that was necessary.

Looking back, clearly Wohlstetter carried the day, leading to Mutually Assured Destruction (MAD) as both the United States and the Soviet Union developed thermonuclear bombs, with yields of hundreds of times the bomb dropped in Hiroshima, Japan, on August 6, 1945.

The 1962 Cuban missile crisis was a wake-up for the leaders in both Washington and Moscow, making them realize how close to the brink they had come. Despite the rivalry, the two nuclear hegemons converged on two issues that were to shape the first nuclear age – the need for strategic stability and the importance of halting the spread of nuclear weapons. The former laid the grounds for nuclear arms control and crisis management and the latter led to negotiations in Geneva resulting in the Nuclear Non-Proliferation Treaty (NPT).

In a world dominated by two nuclear superpowers, both with enormous overkill capacities, strategic stability was equated to nuclear stability. Nuclear stability in turn was based on deterrence stability, managing the nuclear arms race, and fail-safe communications for crisis management.

Thomas Schelling, a Nobel winning economist, applied game theory to nuclear conflict and concluded that while deterrence had to be framed as a system of dynamic adjustment among two rational actors, the uncertainty of “something left to chance” was necessary for credibility. The temptation to undertake an all-out first strike was removed by ensuring “mutual vulnerability” (the 1972 ABM Treaty limited the anti-ballistic missiles that each side could deploy) and symmetry in terms of doctrines and arsenals, thereby giving both adversaries an assured second-strike capability.

In short, irrespective of the steps on the escalation ladder (Herman Kahn designed a 44-step escalation ladder), there would be no winners or losers in a nuclear exchange between the US and Soviet Union.

Hotlines and nuclear risk reduction centers were established for round the clock monitoring of the skies and seas using radars and early warning satellites. Arms control negotiations led to agreements on numbers of strategic launchers and warheads. Though these did little to curb the arms race (the combined nuclear arsenals of the two reached nearly 70,000 in 1986), the dialogue helped manage it and created a semblance of stability. Despite these efforts, there were quite a few close calls; fortunately, common sense and luck ensured that the nuclear taboo was never breached.

The first nuclear age ended with break-up of the Soviet Union in 1991. Russia inherited the Soviet arsenal but the transformed politics dissipated the rivalry. The United States’ unipolar moment, which lasted two decades, led to progressive reductions in nuclear arsenals from a high of 70,000 to approximately 14,000. Russia and the U.S. cooperated to denuclearize Belarus, Kazakhstan, and Ukraine, strengthen export controls on nuclear-related dual-use technologies, focus on threats posed by non-state actors, and extend the NPT into perpetuity (its original span was 25 years).

Deterrence took a back seat as the United States no longer had a nuclear rival. President Barack Obama in 2009 even spoke of “a world without nuclear weapons,” sparking a debate in Washington about moving to a no-first-use policy. However, the second nuclear age turned out to be an interregnum

New technological developments were changing the nature of conflict. The idea of a networked hybrid conflict zone created a seamlessness that blurred the conventional-nuclear firebreak. Dual capable vectors, which could carry conventional or nuclear payloads, were introduced, raising apprehensions about nuclear entanglement.

India and Pakistan went nuclear in 1998. Even as their tense relations led to South Asia being called a nuclear flashpoint, the United states’ conventional global-precision capability and expanded missile defense shield raised doubts in Moscow and Beijing about their nuclear deterrent. North Korea withdrew from the NPT to announce its arrival on the nuclear stage.

Nevertheless, broadly, the non-proliferation consensus held, and the major powers acted in tandem. However, with the return of geopolitical rivalries, both Russia and China embarked on a process of nuclear modernization. The nuclear interregnum that characterized the second nuclear age was ending by the second decade of the 21st century.

The third nuclear age has forced strategic thinkers to confront the dilemma of nuclear deterrence anew, this time in a multipolar nuclear world. For the first time since the end of the Cold War, the United States flagged the nuclear threat it faces, describing Russia as a “disruptive power” seeking a reordering of the “European and Middle East security and economic structures in its favor,” and China as a “pacing challenge” seeking regional hegemony in the Indo-Pacific region in the near term and a “displacement of the US to achieve global pre-eminence in the future.”

Schelling’s notion of making nuclear deterrence credible with “something left to chance” between two rational actors no longer seems reassuring in an age of multiple rivalries characterized by nuclear asymmetry – asymmetry in terms of arsenals, doctrines, and stakes in a future stand-off. Today’s nuclear asymmetry challenges the notions of “parity” and “mutual vulnerability” that had formed the basis of the old Soviet-U.S. arms control, something that China had never bought into.

It’s hardly surprising that the old arms control agreements like the ABM Treaty and the INF Treaty has collapsed and the New START is under strain with no prospects for any talks in the future. Russia’s stakes in Ukraine or China’s in Taiwan open up the temptations for a salami-slicing approach that relies on brinkmanship.

Nuclear saber-rattling by Russia has bounded the Ukraine conflict; NATO has refrained from committing troops even as it continues to assist Ukraine, and Russia has refrained from attacking NATO supply lines. But at the same time, the continuation of the conflict has given rise to speculation about if Russia will resort to tactical nuclear weapons to bring about a termination.

China is widely believed to be undertaking a rapid expansion of its nuclear arsenal, expected to reach 1,000 warheads by 2030, and 1,500 by 2035, indicating that this would be a precursor to a shift away from it no-first-use to a launch-on-warning policy. This has led to Taiwan increasingly emerging as a flashpoint.

The United States issued a new Nuclear Employment Policy in March to implement a congressional recommendation that the U.S. should have the capability to simultaneously deter both China and Russia and (if deterrence failed) to prevail in a conflict. The focus of modernization was on more accurate and low-yield weapons, but these would blur the firebreak and lead to escalation.

Africa, Latin America, and Southeast Asia are self-declared nuclear-weapon-free-zones, but the new conflicts and rivalries are undermining the non-proliferation consensus too. With Sweden and Finland joining NATO, almost all of Europe relies on nuclear security – the United Kingdom and France as nuclear powers and the rest the United States’ extended deterrence. In Asia, Japan and South Korea are less reassured and an internal debate on options is underway. In the Middle East, the U.S. withdrawal from the Joint Comprehensive Plan of Action  has led Iran closer to the nuclear threshold. If Iran moves forward, Saudi Arabia (and perhaps Egypt and Turkey) would want enrichment and reprocessing rights, at the least.

With AI and growing cyber and space capabilities, strategic stability has become too complex to be limited to nuclear stability, but this makes its objective clearer – to preserve the nuclear taboo. Nuclear deterrence in the third nuclear age must be redesigned to work in a multipolar, asymmetric nuclear world where there are multiple nuclear dyads but linked into nuclear chains. 

Since nuclear weapons cannot be wished away, we need to lengthen the nuclear fuse. A doctrinal shift toward a no-first-use and technical measures toward de-alerting can go a long way in mitigating the growing nuclear risks.

The views and opinions expressed in this article are those of the author(s) and do not necessarily reflect those of the Asia Research Institute, National University of Singapore.