The Global Nuclear Balance: Nuclear Forces and Key Trends in Nuclear Modernization

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The CSIS Emeritus Chair is issuing an updated, book-length survey of the trends in the U.S., Russian, and Chinese nuclear balance. It provides an unclassified overview of recent U.S. force planning and intelligence data on U.S. nuclear forces and the Russian and Chinese threats and compares summary estimates of global nuclear and related missile forces by the International Institute for Strategic Studies, the Federation of American Scientists and Bulletin of Atomic Scientists, and CSIS.

It also contains summary data on U.S. force improvement plans taken from the testimony of General Anthony J. Cotton, commander of the U.S. Strategic Command, before the House Armed Services Committee on Strategic Forces on March 8, 2023.

The survey is entitled The Global Nuclear Balance A Comparison of Estimates of Nuclear Forces and Key Trends in Nuclear Modernization, and is available on the CSIS website at

It uses a wide range of summary official and expert estimates of global nuclear forces to illustrate the rapid changes that are now taking place in the global nuclear balance, which are summarized in the slide that follows this page. While it addresses the forces of all the world’s nuclear powers, it focuses on the trends in the United States, Russian, and Chinese nuclear balance. It provides an unclassified overview of recent U.S. official force planning and intelligence data on U.S. Russian, and Chinese nuclear forces; and compares summary estimates of global nuclear and related missile forces by the International Institute for Strategic Studies (IISS), the Federation of American Scientists (FAS), Bulletin of Atomic Scientists, House of Commons Library, U.S. Congressional Research Service (CRS), Stockholm International Peace Research Institute, Royal United Services Institute (RUSI), and Center for Strategic and International Studies (CSIS).

Its final section contains summary data on U.S. force improvement plans taken from the testimony of General Anthony J. Cotton, commander of the U.S. Strategic Command, before the House Armed Services Committee on Strategic Forces on March 8, 2023, and on U.S. plans and strategy on the aspects of missile defense that affect the strategic balance.

Shifts to Three Major Nuclear Powers and Increases in the Strength and Modernization of British, French, Iranian, Israel, Pakistani, and Indian Nuclear Forces

Its main purpose is to illustrate the extent to which nuclear forces have again become a key factor shaping international security, and some of the different ways that experts now portray the changes taking place in nuclear modernization and in the balance between the major powers. It shows that the balance between the major powers has shifted from the nuclear balance between the United States and Russia to one where China is emerging as a nuclear great power; and where important shifts are the shifts taking place in the strength and modernization of other nuclear forces like those of the United Kingdom, France, North Korea, Iran, Israel, India, and Pakistan.

Focusing on the Problems in Estimates Based on Unclassified Data

At the same time, its summary comparisons of different expert assessments highlight the many areas where key data on nuclear forces and nuclear warfighting are not available or present major issues in terms of uncertainty or conflicting data. Such summary data can only illustrate a limited number of the different ways in which experts now estimate the nuclear balance, but the analysis draws upon some of the most respected unclassified sources now available to illustrate the range of data now available and its limitations.

This survey has been substantially updated and expanded as of May 2023 in response to outside comments and suggestions that reviewed an earlier draft, but the estimates it summarizes continue to change and evolve, and the updated data on force strengths in 2023 and on future modernization are especially uncertain. However, even a book-length comparison totaling some 200 pages must ignore much of the work done by the experts it draws upon.

The source of each estimate is listed at the end of each summary, and full text of the work by national governments, Hans M. Kristensen. Matt Korda, Robert Norris, and others in the country-by-country Nuclear Notebooks published in the Bulletin of Atomic Scientists, in the SIPRI annual yearbooks, the various reports by the Congressional Research Service, and the reports by Claire Mills for the House of Commons Library are particularly helpful in comparing different countries, understanding the limits and uncertainties in such data, and the extent to which many estimates are dated, uncertain, or based on uncertain sources.

Limits to the Coverage of this Analysis

Other key limits to the data presented include the fact that the official data on U.S., Russian, Chinese, British, and French programs have consistently tended to underestimate the costs, technical, and delivery date risks in the actual modernization efforts. They also understate the probability of major changes in major national programs as countries deploy new systems warfighting capabilities and change their strategies. Estimates of future forces are also based on current plans that do not reflect in the impact of the war in Ukraine, the collapse of many arms control efforts, and ongoing increases in Chinese forces and tensions over areas like Taiwan and the Koreas.

These serious uncertainties in the data that are available on nuclear weapons and delivery systems. Many of the data on the type of non-U.S. nuclear weapon —fission, boosted, or thermonuclear—and its yield are uncertain. So are the background data on the level of technical sophistication in designing the weapon, upgrades and serving of weapons over the years, and its reliability in a real-world delivery on target.

Data on the actual level of success in each country’s explosive tests of nuclear weapons and progress in weapons design are often uncertain, and so is progress in testing weapons designs using simulated weapons with low levels of enrichment remain classified—although both India and Pakistan are reported to have used such methods. The readiness of stored weapons is not assessed, and the ability to use existing weapons assemblies in missiles and other delivery systems that are normally assessed as having conventional warheads is unknown.

More generally, the summary estimates of existing forces generally only reflect a limited portion of the history of their development, changes in declared national strategy, long-standing questions about the real-world success of given powers in developing advanced systems, the history of arms control efforts, and national nuclear politics. Many of these details are uncertain and debated at the expert level. The narrative summaries of national nuclear efforts in Wikipedia often provide extensive background in these areas but also have serious gaps, are often badly dated, and vary sharply by country in their coverage.

Uncertainties in Data on Delivery Systems

There are few reliable estimates of the changes that most nuclear powers are making to their delivery systems, and much of the data focuses on the performance of individual missiles, aircraft, SSBNs, and potentially dual-capable systems, rather than the numbers to be deployed, actual deployment, and impact on warfighting.

Many of the data on non-U.S. missiles are based on estimates of range based on the type and size of the missile rather than actual flight test data. Estimates of accuracy are often based on the maximum capability of the guidance platform rather than actual missile tests; accuracy is not tied to reliable estimates of nuclear weapons yield, and no reliability data based on actual tests of even the missile system alone are normally available.

Data are lacking on the targeting and retargeting capabilities of given countries, and on their ability to retarget, launch on warning, and accurately detect and characterize nuclear strikes on their own territory and enemy territory, and characterize the difference between counterforce strikes on nuclear and other military forces, and countervalue strikes on civilian populations, key economic and infrastructure targets, and other critical nonmilitary and recovery capabilities.

Failing to Examine Changes in Warfighting Capability

More broadly, the unclassified data now available on nuclear capabilities focus almost exclusively on nuclear delivery systems and nuclear weapons, rather than analyzing actual warfighting capabilities, and the results of a possible nuclear conflict. The unclassified data on nuclear strategy often consists of little more than national political statements about no first use, a desire for arms control, and a focus on deterrence rather than warfighting—none of which may apply in a crisis and at a time when most of the U.S. and Russia nuclear arms control efforts have been canceled or have an uncertain future, China does not participate in meaning arms control negotiation, and smaller nuclear power make statements that are ambiguous and given no clear picture of what might happen in a crisis.

Open-source efforts to analyze the warfighting impact of actual nuclear exchanges largely ended after the collapse of the former Soviet Union, as most tactical and theater nuclear forces were withdrawn from active service, and as arms control seemed to create a truly stable balance of strategic nuclear deterrence. As a result, there are only a handful of credible data on how a nuclear war might now lead to given patterns of counterforce strikes against an opposing side’s nuclear and other military forces, and the impact of fall out and the countervalue impact of counterforce strikes.

There is little recent unclassified analysis of how a nuclear war might lead to countervalue strikes against populations, economies, and recovery capabilities, and of the levels of damage and casualties that might result in a world with radically different economic structures and target bases from that exist at the time of the Cold War. There is also little meaningful open-source analysis of the shifts taking place in key aspects of vulnerability to nuclear attacks, like dependence on imports, manufacturing capability, and changes in the economic value of given cities, key infrastructure targets, and key industrial centers.

Furthermore, only limited data are available on the major changes that have taken place in the ability to use space and other assets to provide reliable warning of attacks, analyze nuclear engagements in near real-time, change counterforce and countervalue targeting dynamically in near real time to reflect the actual course of nuclear exchanges, and assess the value of given counterforce and countervalue targets in both warfighting terms and in terms of recovery capability.

This lack of open-source analysis of the changing nature of actual nuclear warfighting seems increasingly dangerous. China is emerging as a major nuclear power and radically changing the potential nature of nuclear warfare between the major powers. Past efforts to actually analyze nuclear warfighting ignore the fact that there are now three major groups of nuclear forces: the United States, France, the United Kingdom, Russia, and China. This not only presents major problems in modeling the possible patterns in nuclear warfighting and escalation, but it also presents the problem for the United States that any exchange with only Russia or China would make the power that stayed out of the conflict the de facto winner in a major nuclear exchange.

Dual Capability and a Return to Theater Nuclear Warfare

The war in Ukraine has shown that Russia is willing to make nuclear threats, and much of the arms control efforts in Europe and between the United States and Russia have now ended or have an increasingly uncertain future. China has so far refused to engage in arms control negotiations. The end result is that there is a major risk that the deployment of theater nuclear weapons, dual-capable delivery systems that can be armed with nuclear or conventional warheads, and strategic nuclear warheads with yields suitable for theater warfare will increase steadily in the near future. The analysis shows that smaller nuclear powers have remained a relatively limited global threat but pose a steadily growing strategic threat to given nations in their region. Proliferating states like Israel, North Korea, India, and Pakistan are modernizing and increasing their forces, and the potential nuclear efforts of nations like Iran illustrate the rising risk proliferation may pose in the future. North Korea has also been reported to have declared that it has already deployed delivery systems that have both nuclear and conventional warheads.

Other Key Areas of Uncertainty

There are several other major areas of uncertainty that affect the estimates of nuclear forces in this summary analysis:

  • One is proliferation. Key cases involve the steady rise in Indian and Pakistani near force capabilities, the uncertainties surrounding the real-world nuclear capabilities of Israel, North Korean efforts to develop and deploy ICBMs, and the risk of Iran acquiring nuclear weapons and its impact on the development of nuclear forces by Iran’s Arab neighbors.
  • Another is the ways in which nuclear forces can be used in combat and the extent to which the ability to manage a nuclear war in near-real time is becoming far more dynamic. There has been almost no open-source discussion of the potential impact of space sensors, AI, and big data in radically changing the current and future ability to provide reliable launch-on-warning capability and real-time data on the exact nature of nuclear strikes and their effects.
  • These advances in technology may allow the managers of an actual nuclear war to rapidly retarget, shift in near real-time from counterforce to countervalue targets, and fight even the highest levels of nuclear combat dynamically in near real-time. These issues are now being publicly explored in designing forces for advanced forms of conventional Joint All-Domain Operations, but there has been little public discussion of how they might change the modernization of nuclear war fighting.
  • A third area of uncertainty, as the 2023 edition of the ODNI’s Annual Threat Assessment highlights, is the risk that new forms of biological warfare pose a rising strategic threat and one that could be used anonymously and to produce a wide range of lethalities and economic and social effects.
  • A fourth is the fact that most existing U.S. and Russian, and NATO and Russian, arms control agreements have either been halted or suspended, while China has not engaged in arms control negotiations with the United States.
  • A fifth is the fact that the number of precision-strike theater and tactical missiles that are dual capable is steadily increasing, but there is no indication of whether U.S. and Russian tactical and theater nuclear weapons will be returned to active deployment in Europe or elsewhere, and whether today’s U.S., Russian, and Chinese “triads” will become a “quad” that includes theater and dual-capable nuclear forces.
  • Similarly, no reliable estimates exist of the future development and deployment of missile and air defense weapons capable of intercepting nuclear delivery systems, or of cyber, antisatellite, and other systems that can degrade the ability to escalate and conduct nuclear warfare.
  • Finally, as noted earlier, no reliable unclassified estimates seem to exist of the impact that counterforce strikes launched to destroy an opponent’s nuclear forces would have on the opponent’s civil population, economy, and recovery capabilities. Past studies indicated that the real-world difference between counterforce and counter value could be limited by fall-out and longer-term weapons effects in major counterforce exchange, but they are now seriously outdated.
  • It should be noted that the comparative summary analysis in this report shows that few nuclear powers provide full national statements of their nuclear modernization efforts, the full spectrum of their current and future nuclear capabilities, and actual warfighting capabilities. Statements like “no first use” are matters of doctrine that any nation can declare and ignore in a crisis, and no nuclear state has declared possible limits to its uses of nuclear weapons, possible ways in which it might agree to halt nuclear escalation once it begins, and limits to its countervalue targeting.
The Global Nuclear Balance A Comparison of Estimates of Nuclear Forces  and Key Trends in Nuclear Modernization - Table of Content