Updated: August 2018
According to the Federation of the American Scientists, as of February 2018, the United States possesses 4,000 stockpiled strategic and non-strategic nuclear warheads and an additional 2,550 retired warheads awaiting dismantlement, for a total of 6,550 nuclear warheads. On Feb. 2, 2018, the Trump administration released its Nuclear Posture Review, detailing the size and role of U.S. nuclear forces for this administration. The United States has destroyed about 91% of its chemical weapons arsenal as of 2017 and is due to complete destruction by 2023. It is party to the Biological Weapons Convention and has destroyed its biological weapons arsenal, although Russia alleges that U.S. biodefense research violates the BWC.
- The Nuclear Arsenal, an Overview
- Delivery Systems
- Ballistic Missile Defense Systems
- Nuclear Doctrine
- Fissile Material
- Proliferation Record
- New START
- Nuclear Reduction Beyond New START
- Civilian Nuclear Trade with India & the 123 Agreement
- Nuclear Weapons Free Zones
- Nuclear Security Summits
- Syrian Chemical Weapons
- Joint Comprehensive Plan of Action (JCPOA)
Nuclear Nonproliferation Treaty
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Convention on the Physical Protection of Nuclear Material (CPPNM)
CPPNM 2005 Amendment
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International Convention for the Suppression of Acts of Nuclear Terrorism
Signed in 1998, entered into force January, 2009.
Co-founder with Russia
The United States has filed reports on its activities to fulfill the resolutions and volunteered to provide assistance to other states.
The Nuclear Arsenal, an Overview
According to the Federation of the American Scientists, as of February 2018, the United States possesses 4,000 stockpiled strategic and non-strategic nuclear warheads and an additional 2,550 retired warheads awaiting dismantlement, for a total arsenal of 6,550 warheads. Under the 2010 New Strategic Arms Reduction Treaty (New START), the United States can deploy no more than 1,550 treaty accountable strategic warheads until February 2021 when the treaty expires. According to the February 2018 New START data exchange, the United States deploys 1,350 strategic nuclear warheads on 652 ICBMs, SLBMs, and strategic bombers. However, these numbers may be artificially low due to a temporary fluctuation in deployed and non-deployed weapons at the time of the exchange. The United States also deploys an additional 150 tactical (non-strategic) nuclear warheads based in Europe. While the United States and Russia maintain similarly sized total arsenals, the United States possesses a much larger number of strategic warheads and delivery systems while Russia possesses a much larger number of non-strategic (or tactical) nuclear warheads.
The United States has conducted 1,030 total nuclear tests, far more than any other nuclear-armed state. The United States is the only nation to have used nuclear weapons against another country, dropping two bombs (one apiece) on the Japanese cities of Hiroshima and Nagasaki in August 1945.
(For a detailed overview of current and planned U.S. nuclear modernization programs, see our fact sheet here.)
Intercontinental Ballistic Missiles (ICBM)
- As of February 2018, the United States Air Force deploys 400 LGM-30G Minuteman III ICBMs.
- The Minuteman III has a range of over 6,000 miles (9,650-13,000 km).
- Each missile is equipped with either one 300 kt W87 warhead or one 335 kt W78 warhead.
- Under New START, the United States reduced the number of deployed ICBMs from 450 to 400. 50 excess silos have not been destroyed but have been kept in a “warm” operational status and can be loaded with missiles relatively quickly if necessary.
- In 2015, the United States concluded a multibillion dollar, decade-long modernization program that will extend the service life of the Minuteman III to beyond 2030.
- The U.S. Air Force is also developing a new ICBM, known as the ground-based strategic deterrent, which is intended to replace the Minuteman III between 2028 and 2035.
Submarines and Submarine-Launched Ballistic Missile (SLBM)
- The U.S. Navy operates 14 Ohio-class SSBNs submarines, two of which are undergoing overhaul of their nuclear reactors at any given time. The remaining 12 are available for deployment. However, since some operational SSBNs also undergo minor repairs at any given time the actual number of SSBNs at sea usually numbers at around 10.
- 7 submarines are based out of Bangor, Washington and 5 submarines are based out of Kings Bay, Georgia.
- The submarines originally had 24 missile tubes for Trident II D5 SLBMs, but under New START, the Navy deactivated 4 tubes on each submarine, finishing this process in 2017.
- The Ohio-class submarines have a life-span of 42 years.
Trident II D5 submarine-launched ballistic missile
- The Trident II D5 was first deployed in 1990 and has an operational range of 7,400-12,000 km.
- The Trident II D5 missile can hold up to eight warheads (but usually holds an average of four to five) and carries 3 variants:
- the W88—a 475 kt Multiple Independently Targetable Reentry Vehicle (MIRV) warhead.
- the W76-0—a 100 kt MIRV warhead.
- the W76-1—a 100 kt MIRV warhead.
- To comply with New START, the Navy will not deploy more than 240 missiles. As of February 2018, 203 submarine-launched ballistic missiles were deployed.
- An ongoing life extension program is expected to keep the Trident II D5 in service until 2042.
- The Trident II D5 is the only MIRV’ed strategic missile remaining in the U.S. nuclear arsenal.
- As of February 2018, the Air Force deploys 36 nuclear-capable B-52H Stratofortress bombers and 13 nuclear-capable B-2A Spirit bombers.
- The Air Force plans to deploy no more than 60 nuclear-capable strategic bombers under New START.
- An estimated 980 nuclear warheads are assigned to the strategic bombers, but only about 300 are typically deployed at bomber bases.
- The United States also maintains several fighter-aircraft that serve in a dual-capable role. The F-15E and F-16C have been the cornerstone of this aspect of nuclear deterrence, carrying the B61 gravity bomb. The new stealth F-35 Lightning II, also known as the Joint Strike Fighter, will replace the F-16 as the U.S. Air Force’s primary nuclear capable fighter-aircraft.
The 2018 Nuclear Posture Review (NPR), released on Feb. 2, 2018, details the Trump administration’s approach to the size and role of U.S. nuclear forces. Deputy Defense Secretary Patrick Shanahan, in a Feb. 2, 2018 press briefing, claimed that the 2018 NPR “reaffirms that the fundamental role of U.S. nuclear policy is deterrence.” Critics of the document argue that the NPR reverses previous policy to reduce the role and number of U.S. nuclear weapons.
The NPR dictates that the use of nuclear weapons will only be considered under “extreme circumstances” to defend the “vital interests” of the United States and its allies. It defines “extreme circumstances,” which the 2010 NPR did not, to include “significant non-nuclear strategic attacks” against “U.S., allied or partner civilian population or infrastructure, and attacks on U.S. or allied nuclear forces, their command and control, or warning and attack assessment capabilities.” For more on declaratory policy, see: Nuclear Declaratory Policy and Negative Security Assurances.
Negative Security Assurance
The NPR also includes a negative security assurance that the United States will not use nuclear weapons against non-nuclear-weapons states that are “party to the nuclear Nonproliferation Treaty and are in compliance with their nuclear nonproliferation obligations.” It caveats its negative security assurance by retaining “the right to make any adjustment in the assurance that may be warranted by the evolution and proliferation of non-nuclear strategic attack technologies and U.S. capabilities to counter that threat.” For more on negative security assurances, see: U.S. Negative Security Assurances at a Glance.
Ballistic Missile Defense Systems
The United States develops and deploys several ballistic missile defense systems around the world. To learn more, see: "U.S. Missile Defense Programs at a Glance."
Highly Enriched Uranium (HEU)
- The United States has publicly declared that it no longer produces fissile material for weapons purposes. It stopped production of HEU in 1992.
- In March 2016, the United States announced the declassification of its national inventory of highly enriched uranium (HEU), as of September 30, 2013.
- The United States halted the production of HEU for weapons in 1964 and ceased plutonium separation for weapons in 1992.
- Estimates from 2016 place the U.S. HEU stockpile at around 600 metric tons, including 253 metric tons of military HEU and 264 metric tons of fresh and spent naval HEU.
- According to the 2015 Global Fissile Material Report, the United States has about 40 metric tons of HEU remaining to be downblended of the 187 metric tons it declared as excess to defense requirements and has committed to dispose.
- The United States ended production of separated plutonium in 1988.
- At the end of 2014, U.S. military plutonium stockpiles amounted to a total of 87.6 declared metric tons (49.3 metric tons of which are declared as excess military plutonium).
- In October 2016, citing U.S. failure to meet its obligations under the agreement, Russia suspended its own implementation of the deal. Russia refuses to resume the agreement’s implementation until U.S. sanctions against Russia are lifted and NATO forces in Europe are reorganized along lines favorable to Russia. Russia contends that U.S. plans to abandon the conversion of plutonium into MOX fuel in favor of a cheaper and faster downblending method does not meet the terms of the deal because doing so would fail to change the composition of the plutonium from weapons grade to reactor grade.
- The United States possesses no separated civilian plutonium but at the end of 2014, an estimated 625 metric tons of plutonium were contained in spent fuel stored at civilian reactor sites.
- Under the Plutonium Management and Disposition Agreement (PMDA), finalized with Russia in 2000, the United States committed to disposing of 34 metric tons of excess weapons-grade plutonium beginning in 2018. The agreement was amended in 2010 to change the agreed disposition methods in which Russia abandoned using mixed-oxide (MOX) fuel in light-water reactors in favor or irradiating plutonium in its fast-neutron reactors. The amendment also expressed renewed U.S. commitment to provide $400 million towards the Russian disposition program. Russia suspended cooperation with the agreement in November 2016.
- A close relationship exists between U.S. and British nuclear weapons programs. The United States supplies the United Kingdom with the Trident II D5 SLBM.
- Belgium, Germany, Italy, the Netherlands, and Turkey all host U.S. tactical nuclear gravity bombs as part of NATO nuclear sharing agreements. The estimated 180 weapons remain under U.S. custody during peacetime, but some may be released to U.S. allies for delivery in times of war.
- Beginning with President Dwight Eisenhower’s 1953 “Atoms for Peace” initiative, the United States has engaged in extensive worldwide trading and exchanging of fissile materials and technical information for nuclear science research and the peaceful use of nuclear technology. In 1954, an amendment to the Atomic Energy Act allowed bilateral nuclear agreements with U.S. allies to proceed, with the intent of exporting only low enriched uranium (LEU) fuel; however, this soon expanded to include HEU.
- Under the “Atoms for Peace” program a number of former, aspiring, and current nuclear weapon-states such as South Africa, Iran, India, Pakistan, and Israel all received, directly or indirectly, training and technology transfers utilized in their nuclear weapons programs. For example, in 1967, the United States supplied Iran with a 5 megawatt nuclear research reactor along with HEU fuel. Iran admitted to using the reactor in the early 1990s for the production of small amounts of Polonium-210, a radioactive substance capable of starting a chain reaction inside a nuclear weapon.
- Since the end of the Cold War the United States has tried to mitigate the adverse effects of the “Atoms for Peace” initiative and returned exported HEU and plutonium to the United States.
- In the early 1970s, the United States destroyed its entire stockpile of biological weapons, which had been developed between 1943 and 1969.
- In 2001, the Bush administration opposed and killed an effort dating back to 1995 to augment the Biological Weapons Convention with a legally binding verification protocol. U.S. officials said the protocol would be too burdensome on legitimate governments and private biodefense programs, while at the same time failing to deter cheaters.
- According to a 2016 State Department report, “In December 2015 at the annual Meeting of States Parties to the BWC, the delegation of the Russian Federation asserted that the United States had knowingly transferred live anthrax spores to a foreign country for use in open-air testing, and that this constituted a ‘grave violation’ of Articles III and IV of the BWC [Biological Weapons Convention].”
- The United States maintains that these transfers were a blunder. The report also notes that, “All U.S. activities during the reporting period were consistent with the obligations set forth in the BWC. The United States continues to work toward enhancing transparency of biological defense work using the BWC confidence building measures.”
- Behind Russia, the United States has declared the second-largest stockpile of chemical agents.
- As of Oct. 31, 2017, the United States had destroyed 25,154 metric tons, or about 91 percent, of its declared Category 1 chemical weapons stockpile. The United States has completed destruction of all its Category 2 and 3 chemical weapons.
- The United States received several extensions on its initial deadline for chemical weapons destruction under the Chemical Weapons Convention, and it now due to destroy its chemical weapons arsenal by 2023.
- Destruction of the United States’ largest remaining stockpile of chemical weapons began in March of 2015 at Colorado’s Pueblo Chemical Depot. Upon completion, the Blue Grass Army Depot in Richmond, Kentucky will have the last remaining chemical agent stockpile in the United States.
In April 2010, the United States and Russia signed a successor agreement to the original Strategic Arms Reduction Treaty (START) accord. The 2010 agreement, known as New START, commenced on Feb. 5, 2011. It requires that both sides reduce their arsenals to 1,550 deployed strategic nuclear weapons on no more than 700 ICMBs, SLMBs, and bombers by Feb. 5, 2018 and both sides met the limits by the deadline. In addition, it contains rigorous monitoring and verification provisions to ensure compliance with the agreement. President Donald Trump has repeatedly questioned the value of New START, calling it a “one-sided” agreement.
Nuclear Reduction Beyond New START
In February 2013, President Obama announced that the United States intended to engage with Russia to further reduce deployed strategic warheads by one-third below the New START limit to around 1,100 to 1,000 deployed warheads. However, there has been little progress toward achieving such reductions due to the deterioration of U.S.-Russia relations in the aftermath of Russia’s annexation of Crimea and Russia’s insistence that other issues, such as limits on U.S. missile defenses, be part of negotiations on further reductions.
Civilian Nuclear Trade with India & the 123 Agreement
In July 2005, the United States signed a controversial agreement with India to repeal most U.S. and multilateral civilian nuclear trade restrictions on India. In 2006, Congress amended its own domestic legislation to allow nuclear trade with India to proceed. The two governments later concluded a “123 Agreement,” which was approved by Congress and signed into law in October 2008. In September 2008, India received a waiver from the Nuclear Suppliers Group (NSG). The United States has pushed for India to become a member of the NSG, but in January 2017, China and other countries blocked India's membership bid on the grounds that India has not yet signed the NPT.
Nuclear Weapons Free Zones
The United States has ratified a protocol to the Latin America and the Caribbean Nuclear Weapons Free Zone (NWFZ) treaty pledging not to use or threaten to use nuclear weapons against the contracting parties. The U.S. has declined to ratify similar additional protocols to any of the remaining NWFZ treaties for Africa, Central Asia, Southeast Asia, and the South Pacific.
Nuclear Security Summits
In April 2010, the United States hosted the first Nuclear Security Summit (NSS) in Washington, DC. Participants included 47 countries, 38 of which were represented at the head of state or head of government level, and the heads of the United Nations, the International Atomic Energy Agency, and the European Union. At the summit, the participants unanimously adopted the goal of securing all vulnerable nuclear material in the next four years. The United States also attended the NSS in Seoul, South Korea, on March 26-27, 2012 and the third NSS on Mar. 24-25, 2014. Washington hosted a fourth summit in the Spring of 2016 where attendees developed action plans for five global organizations to continue the work of the summits.
Syrian Chemical Weapons
In September 2013, in the aftermath of the large-scale use of chemical weapons by the Syrian government, United States reached an agreement with Russia to account, inspect, control, and eliminate Syria’s chemical weapons. Before the deal was reached, the United States was planning to use airstrikes to punish the perpetrators of the attack, which the United States blamed on the Syrian government. By July 2014, Syria’s declared chemical weapons stockpile had been successfully removed from the country and flagged for destruction following a broad multilateral operation. However, the United States has raised concerns about the accuracy of Syria’s declaration.
In September 2014, the Organisation for the Prohibition of Chemical Weapons (OPCW) confirmed that chlorine gas was being used in Syria. The UN Security Council adopted a resolution on Mar. 6, 2015 condemning the use of chlorine gas in Syria. Secretary of State John Kerry was quick to suggest that the Assad regime was the likely perpetrator of the chlorine gas attacks; Russia, however, was hesitant to assign blame. In August 2016, the third report of the OPCW-UN Joint Investigative Mechanism was released, finding that the Syrian government was responsible for chemical weapons attacks.
In April 2017, another chemical weapon attack was carried out in the Syrian town of Khan Shaykhun where Syrian government warplanes were accused of spreading a nerve agent via bombs, killing dozens. U.S. President Donald Trump responded by immediately blaming the regime of Bashar Assad and launching 59 Tomahawk missiles targeting the airfield that had allegedly launched the. Following the launches, Trump stated that “It is in this vital national security of the United States to prevent and deter the spread and use of deadly chemical weapons.” As a justification for the U.S. response, Secretary of State Rex Tillerson stated that “If you violate international agreements, if you fail to live up to commitments, if you become a threat to others, at some point a response is likely to be undertaken.”
(For a detailed timeline on Syrian chemical weapons, see our fact sheet here.)
Joint Comprehensive Plan of Action (JCPOA)
Under the Obama administration the United States played the central role in the brokering of the July 2015 JCPOA, better known as the “Iran deal,” which limits and rolls back Iran’s nuclear program in exchange for lifting economic sanctions. Congress in September 2015 debated a resolution that would have blocked implementation of the accord, but it failed to receive enough votes to pass the Senate. In January 2016, financial and oil sanctions on Iran were lifted along with the release of $100 billion worth of frozen Iranian assets after international inspectors confirmed that Iran had rolled back large sections of its nuclear program. In an effort to preserve the deal before leaving office, the Obama administration worked to fend off additional sanctions and encouraged American companies to conduct business in Iran.
On May 8, President Trump violated the JCPOA by committing to re-impose sanctions on Iran that were lifted by the agreement. After President Trump announced that he was withdrawing the United States from the deal, the other parties to the agreement decided to continue to implement their obligations.
Conference on Disarmament (CD)
The Conference on Disarmament was established in 1979 as a multilateral disarmament negotiating forum by the international community. At the 65-member CD, the United States has expressed support for continuing discussions on the CD's core issues: nuclear disarmament, a fissile material cut-off treaty (FMCT), prevention of an arms race in outer space (PAROS), and negative security assurances. The United States has been a prominent supporter of a proposed FMCT.
In March 1995, the CD took up The Shannon Mandate which established an ad hoc committee directed to negotiate an FMCT by the end of the 1995 session. A lack of consensus over verification provisions, as well as desires to hold parallel negotiations on outer space arms control issues, prevented negotiations from getting underway. Later, in May 2006, the United States introduced a draft FMCT along with a draft mandate for its negotiations. However, following an impasse in negotiations on a FMCT in 2010, the United States (and others) signaled its desire to look at alternative approaches outside the CD and called for negotiations to be moved to the United Nations General Assembly where the agreement could be endorsed by a majority vote. However, the United States no longer makes comments to this effect.
The United States does not support negotiations on PAROS, deeming it unnecessary because there are no weapons yet deployed in outer space. China and Russia continue to articulate a desire to hold parallel negotiations, a point which has further stalled efforts to begin FMCT negotiations.