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The Nuclear Notebook is researched and written by Hans M. Kristensen, director of the Nuclear Information Project with the Federation of American Scientists, and Robert S. Norris, a senior fellow with the FAS. The Nuclear Notebook column has been published in the Bulletin of the Atomic Scientists since 1987. This issue's column examines Pakistan's nuclear arsenal, which includes 140 to 150 warheads. The authors estimate that the country's stockpile could realistically grow to 220 to 250 warheads by 2025, if the current trend continues. [ABSTRACT FROM AUTHOR]

The Nuclear Notebook is researched and written by Hans M. Kristensen, director of the Nuclear Information Project with the Federation of American Scientists, and Robert S. Norris, a senior fellow with the FAS. The Nuclear Notebook column has been published in the Bulletin of the Atomic Scientists since 1987. This issue's column examines China's nuclear arsenal, which includes about 280 warheads for delivery by ballistic missiles and bombers. This stockpile is likely to grow further over the next decade. [ABSTRACT FROM AUTHOR]

The Nuclear Notebook is researched and written by Hans M. Kristensen, director of the Nuclear Information Project with the Federation of American Scientists, and Robert S. Norris, a senior fellow with the FAS. The Nuclear Notebook column has been published in the Bulletin of the Atomic Scientists since 1987. This issue’s column examines Russia’s nuclear arsenal, which includes 4,350 warheads that can be delivered via long-range strategic launchers and shorter-range tactical nuclear forces. [ABSTRACT FROM AUTHOR]

The US nuclear arsenal remained roughly unchanged in the last year, with the Defense Department maintaining an estimated stockpile of some 4,000 warheads to be delivered via ballistic missiles and aircraft. Most of these warheads are not deployed but stored, and many are destined to be retired. Of the approximately 1,800 warheads that are deployed, roughly 1,650 are on ballistic missiles or at bomber bases in the United States, with another 150 tactical bombs deployed at European bases. [ABSTRACT FROM AUTHOR]

The authors cautiously estimate that North Korea may have produced enough fissile material to build between 30 and 60 nuclear weapons, and that it might possibly have assembled 10 to 20. Although North Korea is thought to have the capability to develop an operationally functioning re-entry vehicle to deliver an operational nuclear warhead, there is some uncertainty about whether it has demonstrated that it has succeeded in doing so. Nonetheless, North Korea’s nuclear weapons program has made considerable progress over the years, including a wide variety of ballistic and powerful nuclear tests. Presumably, if it hasn't happened already, it is only a matter of time before Pyongyang’s nuclear arsenal can be considered fully functioning. [ABSTRACT FROM PUBLISHER]

During the Cold War, the United States deployed nuclear weapons in South Korea continuously for 33 years, from 1958 to 1991. The South Korean-based nuclear arsenal peaked at an all-time high of approximately 950 warheads in 1967. Since the last US nuclear weapons were withdrawn from South Korea in 1991, the United States has protected South Korea and Japan under a “nuclear umbrella” using nuclear bombers and submarines based elsewhere. While defense hawks in Seoul and Washington have, in 2017, called for the United States to redeploy tactical nuclear weapons to South Korea, the authors argue against this idea. Doing so, they say, would provide no resolution of the crisis over North Korea’s nuclear weapons and would likely increase nuclear risks. Redeployment would also have serious implications for broader regional issues because it would likely be seen by China and Russia as further undermining their security. [ABSTRACT FROM PUBLISHER]

The authors estimate that as of mid-2017, there are nearly 15,000 nuclear weapons in the world, located at some 107 sites in 14 countries. Roughly, 9400 of these weapons are in military arsenals; the remaining weapons are retired and awaiting dismantlement. Nearly 4000 are operationally available, and some 1800 are on high alert and ready for use on short notice. This article reviews the locations of nuclear weapons in all nine nuclear-armed states, as well as those of US weapons deployed outside the United States. [ABSTRACT FROM AUTHOR]

India continues to modernize its nuclear arsenal, with at least four new weapon systems now under development to complement or replace existing nuclear-capable aircraft, land-based delivery systems, and sea-based systems. India is estimated to have produced enough plutonium for 150–200 nuclear warheads but has likely produced only 120–130. Nonetheless, additional plutonium will be required to produce warheads for missiles now under development, and India is reportedly building two new plutonium production facilities. India’s nuclear strategy, which has traditionally focused on Pakistan, now appears to place increased emphasis on China. [ABSTRACT FROM PUBLISHER]

Russia is in the middle of a broad modernization of its strategic and nonstrategic nuclear forces, including both new programs and some that have been underway for many years. As of early 2017, the authors estimate that Russia has a military stockpile of roughly 4,300 nuclear warheads assigned for use by long-range strategic launchers and shorter-range tactical nuclear forces. Of these, roughly 1,950 strategic warheads are deployed on ballistic missiles and at heavy bomber bases, while another 500 strategic warheads are in storage along with some 1,850 nonstrategic warheads. In addition to the military stockpile for operational forces, a large number of retired but still largely intact warheads await dismantlement, for a total inventory of around 7,000 warheads. The modernizations, combined with an increase in the number and size of military exercises and occasional explicit nuclear threats against other countries, contribute to growing concern abroad about Russian intentions. These concerns, in turn, drive increased defense spending, nuclear modernization programs, and political opposition to reductions in Western Europe and the United States. [ABSTRACT FROM AUTHOR]

THE UNITED STATES PLANS TO begin deployment of a limited ballistic missile defense system at Fort Greely in Alaska and Vandenberg Air Force Base in California by the end of [...]

Ballistic missiles. China operates approximately 120 ballistic missiles of four types: the DF-3A, DF-4, DF-5/5A, and DF-21A. Each missile carries a single nuclear warhead. China is gradually retiring its DF-3A [...]

KEY EVENTS THAT AFFECTED U.S. NUCLEAR forces over the past year included the signing of the Strategic Offensive Reductions Treaty (the 'Moscow Treaty') by Presidents George W. Bush and Vladimir [...]

AFTER ONE YEAR IN OFFICE, IN JANUARY 2002 the Bush administration completed the Nuclear Posture Review (NPR). Although classified, the review was leaked in early March. It outlines the Pentagon's […]

The US nuclear arsenal remained roughly unchanged in the last year, with the Defense Department maintaining an estimated stockpile of some 4,480 warheads to be delivered via ballistic missiles and aircraft. Since September 2009, when the United States announced that the nuclear arsenal contained 5,113 warheads, the stockpile has decreased by 633. Most warheads in the current arsenal are not deployed but stored, and many are destined to be retired. Of the approximately 1,740 warheads deployed, roughly 1,590 are on ballistic missiles or at bomber bases in the United States, with another 150 tactical bombs deployed at European bases. The number of US deployed strategic warheads has decreased since September 1, 2016. [ABSTRACT FROM PUBLISHER]

Pakistan has a nuclear weapons stockpile of 130–140 warheads and appears to have plans to increase its arsenal further. With several delivery systems in development, four plutonium production reactors, and expansion of uranium enrichment facilities, the country’s stockpile will likely increase over the next 10 years, but by how much will depend on many things. Two key factors will be how many nuclear-capable launchers Islamabad plans to deploy, and how much the Indian nuclear arsenal grows. Based on Pakistan’s performance over the past 20 years and its current and anticipated weapons deployments, the authors estimate that its stockpile could potentially grow to 220–250 warheads by 2025, making it the world’s fifth-largest nuclear weapon state. Pakistan’s deployment of short-range, so-called tactical nuclear weapons is causing considerable concern in South Asia and in the US Government about warhead security and lowering of the threshold for nuclear weapons use. [ABSTRACT FROM PUBLISHER]

The modernization of China’s land-based nuclear-capable missile force has progressed significantly over the past year, with Beijing fielding a new version of an existing nuclear missile and a new dual-capable missile. The country has also reorganized its nuclear missile command structure. The authors estimate that, in total, China has a stockpile of approximately 260 nuclear warheads for delivery by nearly 150 land-based ballistic missiles, 48 sea-based ballistic missiles, and bombers. The Chinese intercontinental ballistic missile (ICBM) force will probably continue to grow slowly, such that the number of ICBM warheads primarily targeted against the United States may exceed 100 a decade from now. Although there is no sign that the Chinese government has officially diverted from its no-first-use nuclear policy, its modernization program is adding significant new capabilities. These qualitative improvements may in turn alter Chinese nuclear policy and strategy. [ABSTRACT FROM AUTHOR]

Russia is in the middle of a broad modernization of its strategic and nonstrategic nuclear forces, including some new developments. The authors estimate that as of early 2016, the country had a stockpile of approximately 4500 nuclear warheads assigned for use by long-range strategic launchers and shorter range tactical nuclear forces. In addition, as many as 2800 retired but still largely intact warheads awaited dismantlement, for a total inventory of about 7300. The modernization program reflects the government's conviction that strategic nuclear forces are indispensible for Russia's security and status as a great power. Unless a new arms reduction agreement is reached in the near future, the shrinking of Russia's strategic nuclear arsenal that has characterized the past two decades will likely come to an end, with the force leveling out at around 500 launchers with roughly 2400 assigned warheads. Combined with an increased number of military exercises and operations, as well as occasional explicit nuclear threats against other countries, the modernizations contribute to growing concern abroad about Russian intentions. [ABSTRACT FROM AUTHOR]

The US nuclear arsenal remained roughly unchanged in the last year, with the Defense Department maintaining an estimated stockpile of some 4,670 warheads to be delivered via ballistic missiles and aircraft. Most of these warheads are not deployed but stored, and many are destined to be retired. Of the approximately 1,930 warheads that are deployed, roughly 1,750 are on ballistic missiles or at bomber bases in the United States, with another 180 tactical bombs deployed at European bases. [ABSTRACT FROM AUTHOR]

Newly declassified documents from the US Defense Department show how many nuclear weapons the United States deployed at sea between 1953 and 1991. The documents, which give totals for the Atlantic Ocean, Pacific Ocean, and Mediterranean Sea, show that the number of US nuclear weapons afloat peaked in 1975 at 6,191 warheads, at the time nearly 23 percent of the US nuclear weapons stockpile. From 1974 to 1991, US fleets at sea routinely carried more than 5,000 nuclear weapons in total, or approximately 20 percent of the entire nuclear weapons stockpile. In 1991, US President George H. W. Bush decided to off-load all nonstrategic nuclear weapons from the fleet, a task completed in 1992. The number of US nuclear weapons currently at sea remains an official secret, but the authors have estimated the number of deployed warheads on ballistic missiles to create an extended timeline through 2015. [ABSTRACT FROM AUTHOR]

Pakistan has a nuclear weapons stockpile of 110 to 130 warheads, an increase from an estimated 90 to 110 warheads in 2011. With several delivery systems in development, four operating plutonium production reactors, and uranium facilities, the country’s stockpile will likely increase over the next 10 years, but by how much will depend on many things. Two key factors will be how many nuclear-capable launchers Islamabad plans to deploy, and how much the Indian nuclear arsenal grows. Based on Pakistan’s performance over the past 20 years and its current and anticipated weapons deployments, the authors estimate that its stockpile could realistically grow to 220 to 250 warheads by 2025, making it the world’s fifth largest nuclear weapon state. Pakistan appears to have six types of currently operational nuclear-capable ballistic missiles, plus at least two more under development: the short-range Shaheen-1A and medium-range Shaheen-3. Pakistan is also developing two new cruise missiles, the ground-launched Babur (Hatf-7) and the air-launched Ra’ad (Hatf-8). [ABSTRACT FROM AUTHOR]

With several long-range ballistic missiles in development, the Indian nuclear posture is entering an important new phase. After nearly two decades of focusing on nuclear competition with Pakistan, New Delhi seems to now be paying attention to its future strategic relationship with China. India is estimated to have produced approximately 540 kilograms of weapon-grade plutonium, enough for 135 to 180 nuclear warheads, though not all of that material is being used. The authors estimate that India has produced between 110 and 120 nuclear warheads. The country’s fighter-bombers still constitute the backbone of its operational nuclear strike force, but it has made considerable progress in developing credible land-based ballistic missiles as well. They include the Agni-4, which will be capable of delivering a single nuclear warhead more than 3,500 kilometers, and therefore able to strike Beijing and Shanghai from northern India. In 2014, India conducted its first ever sea trial of a nuclear-powered ballistic missile submarine. [ABSTRACT FROM AUTHOR]

China is the only one of the five original nuclear weapon states that is quantitatively increasing the size of its nuclear arsenal and it now is estimated to have approximately 260 warheads. The arsenal’s capabilities are also increasing as older missiles are replaced with newer ones. As China assigns a growing portion of its warheads to long-range missiles, the US intelligence community predicts that by the mid-2020s the number of warheads on missiles capable of threatening the United States could increase to well over 100. The nuclear warheads in the Chinese stockpile are intended for delivery mainly by land-based ballistic missile but also by aircraft and submarines. The current force has nearly 150 nuclear-capable land-based missiles, half of which are short-range and medium-range. China has also built two types of submarine-launched ballistic missiles, one developed for a submarine no longer considered operational and the other in the final stages of development. [ABSTRACT FROM AUTHOR]

Russia is modernizing its strategic and nonstrategic nuclear warheads. It currently has 4,500 nuclear warheads, of which roughly 1,780 strategic warheads are deployed on missiles and at bomber bases. Another 700 strategic warheads are in storage along with roughly 2,000 nonstrategic warheads. Russia deploys an estimated 311 ICBMs that can carry approximately 1,050 warheads. It is in the process of retiring all Soviet-era ICBMs and replacing them with new systems, a project that according to Moscow is about halfway complete. The outgoing ICBMs will be replaced by the SS-27 Mod. 1 (Topol-M), the SS-27 Mod. 2, two follow-on versions of the SS-27 which are still in development, and a new liquid-fuel “heavy” ICBM. Following technical problems, the Russian Navy is also rolling out its new Borey-class nuclear-powered ballistic missile submarine. Russia’s upgrades to its nuclear arsenal help justify modernization programs in other nuclear weapon states, and raise questions about Russia's commitment to its obligations under the nuclear Non-Proliferation Treaty to reduce and eliminate nuclear weapons. [ABSTRACT FROM PUBLISHER]

As of early 2015, the authors estimate that the US Defense Department maintains about 4,760 nuclear warheads. Of this number, they estimate that approximately 2,080 warheads are deployed while 2,680 warheads are in storage. In addition to the warheads in the Defense Department stockpile, approximately 2,340 retired but still intact warheads are in storage under the custody of the Energy Department and awaiting dismantlement, for a total US inventory of roughly 7,100 warheads. Since New START entered into force in February 2011, the United States has reported cutting a total of 158 strategic warheads and 88 launchers. It has plans to make some further reductions by 2018. Over the next decade, it also plans to spend as much as $350 billion on modernizing and maintaining its nuclear forces. [ABSTRACT FROM AUTHOR]

WE ESTIMATE THAT AS OF JANUARY 2005 there are approximately 5,300 operational nuclear warheads in the U.S. stockpile, including 4,530 strategic warheads and 780 non-strategic warheads. Almost 5,000 additional warheads [...]

THE PAST YEAR HAS SEEN A RENEWED interest in nuclear weapons by President Vladimir Putin and the Russian military. There are several reasons for this: the abandonment of the START [...]

IN SPRING 2004, THE U.S. STOCKPILE contained approximately 7,000 operational nuclear warheads, including 5,886 strategic and 1,120 non-strategic warheads. Some 3,000 additional warheads are held in reserve, with a few [...]

SINCE THE END OF THE COLD WAR, the main activity at the Pantex Plant in Texas has been dismantling warheads removed from the U.S. nuclear stockpile. Over the next decade, [...]

Over 28 years of weapons analysis, the Nuclear Notebook column has revealed surprise nuclear activity and spot-on arsenal estimates while becoming a daily resource for scholars, activists, and journalists. The authors trace the development of the Notebook as part of the Bulletin of the Atomic Scientists special issue celebrating its 70th year of publication. [ABSTRACT FROM PUBLISHER]

Although the Israeli government neither confirms nor denies that it possesses nuclear weapons, it is generally accepted by friend and foe alike that Israel is a nuclear-armed state—and has been so for nearly half a century. The basis for this conclusion has been strengthened significantly since our previous estimate in 2002, particularly thanks to new documents obtained by scholars under the US Freedom of Information Act and other openly available sources.1 We conclude that many of the public claims about the size of the Israeli nuclear arsenal are exaggerated. We estimate that Israel has a stockpile of approximately 80 nuclear warheads for delivery by two dozen missiles, a couple of squadrons of aircraft, and perhaps a small number of sea-launched cruise missiles. [ABSTRACT FROM AUTHOR]

As of mid-2014, the authors estimate that there are approximately 16,300 nuclear weapons located at some 98 sites in 14 countries. Roughly 10,000 of these weapons are in military arsenals; the remaining weapons are retired and awaiting dismantlement. Approximately 4,000 are operationally available, and some 1,800 are on high alert and ready for use on short notice. The largest concentrations of nuclear weapons reside in Russia and the United States, which possess 93 percent of the total global inventory. The United States today stores nuclear weapons at 18 sites, including 12 sites in 11 states in the United States and another six sites in five European countries. There is considerable uncertainty about the number of Russian nuclear weapons storage sites, but the authors estimate that Russia today stores nuclear weapons permanently at 40 domestic locations. [ABSTRACT FROM AUTHOR]

The nuclear-armed states have large residual nuclear arsenals, and post-Cold War reductions of nuclear weapons have slowed. Meanwhile, the nuclear nations have undertaken ambitious nuclear weapon modernization programs that threaten to prolong the nuclear era indefinitely. These trends present a challenge to the Nuclear Non-Proliferation Treaty community, appearing to contradict the promises by the five NPT nuclear-weapon states to pursue a halt to the nuclear arms race and to seek nuclear disarmament. The NPT does not explicitly place limitations on modernizations, but the 2015 NPT Review Conference will have to address whether extending the nuclear arsenals in perpetuity is consistent with the obligations under NPT's Article VI and the overall purpose of the treaty. [ABSTRACT FROM AUTHOR]

The Obama administration has approved an upgrade to the B61 nuclear bomb that will, through use of a new tail kit assembly, become a guided standoff nuclear bomb. If the upgrade—the 12th modification of the original B61 design—is pursued as planned, the US Air Force will obtain the low-yield, precision-guided nuclear weapon it first sought in the 1990s, despite concerns that it could increase the likelihood of use. The weapon’s overall price tag is expected to exceed $10 billion, with each B61-12 estimated to cost more than the value of its weight in gold. [ABSTRACT FROM PUBLISHER]

Russia has taken important steps in modernizing its nuclear forces since early 2013, including the continued development and deployment of new intercontinental ballistic missiles (ICBMs), construction of ballistic missile submarines, and development of a new strategic bomber. As of March 2013, the authors estimate, Russia had a military stockpile of approximately 4,300 nuclear warheads, of which roughly 1,600 strategic warheads were deployed on missiles and at bomber bases. Another 700 strategic warheads are in storage along with roughly 2,000 nonstrategic warheads. A large number—perhaps 3,500—of retired but still largely intact warheads await dismantlement. [ABSTRACT FROM PUBLISHER]

AS OF MID-2003, RUSSIA HAS APproximately 8,250 operational nuclear warheads in its arsenal. This includes about 4,850 strategic warheads, representing a slight decrease from last year's level due to the [...]

THE B61 BOMB IS PERHAPS THE MOST versatile and abundant nuclear weapon in the U.S. stockpile. Close study of its complex history reveals something that the nuclear weapon labs may [...]

As OF MID-2002, RUSSIA WAS BELIEVED to have an arsenal of approximately 8,400 operational nuclear warheads: almost 5,000 deployed on strategic nuclear weapons systems, and nearly 3,400 non-strategic and air [...]

THE SIZE AND COMPOSITION OF INDIA'S nuclear arsenal is difficult to determine. From various sources, we estimate that India has a stockpile of approximately 30-35 nuclear warheads (fewer than Pakistan), […]

The United States has an estimated 4,650 nuclear warheads available for delivery by more than 800 ballistic missiles and aircraft. Approximately 2,700 retired but still intact warheads await dismantlement, for a total inventory of roughly 7,400 warheads. The stockpile includes an estimated 2,130 operational warheads, about 1,150 on submarine-launched ballistic missiles and 470 on intercontinental ballistic missiles. Roughly 300 strategic warheads are located at bomber bases in the United States, and nearly 200 nonstrategic warheads are deployed in Europe. Another 2,530 warheads are in storage. To comply with New START, the United States is expected to eliminate land-based missile silos, reduce the number of launch tubes on its missile submarines, and limit its inventory of nuclear-capable bombers in coming years. Coinciding with a revised nuclear weapons strategy, the Obama administration is also planning an upgrade of all nuclear weapons systems. The three-decade-long plan would cost more than $200 billion in the first decade alone. [ABSTRACT FROM AUTHOR]