Updated: January 2018
According to the most recent announcement provided by the Obama administration in January 2017, as of September 2016 the United States possessed 4,018 nuclear warheads and an additional 2,800 retired warheads awaiting dismantlement. The U.S. has already met its New START requirements to reduce its deployed warheads to 1,550 by 2018, and according to the September 2017 New START data exchange it has 1,393 strategic nuclear warheads deployed on 660 ICBMs, SLBMs, and strategic bombers, with an additional 150-200 tactical warheads deployed in Europe. President Trump ordered a new Nuclear Posture Review in January 2017, and the Defense Department is expected to release the NPR early in 2018. The United States has destroyed about 90% of its chemical weapons arsenal as of 2016 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
- 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
Under President Barack Obama, the United States began declassifying the size of its military nuclear stockpile. The most recent update provided by the Obama administration in January 2017 indicates that, as of September 30, 2016, the United States had 4,018 nuclear warheads in its military stockpile, including tactical, strategic, and non-deployed weapons. The administration also announced that an additional 2,800 retired warheads are awaiting dismantlement, putting the total size of the U.S. warhead stockpile at 6,800 warheads. 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.
Under the 2010 New Strategic Arms Reduction Treaty (New START), the United States will reduce its deployed treaty accountable strategic warheads to 1,550 by the treaty implementation deadline of 2018. According to the September 2017 New START data exchange, the United States has 1,393 strategic nuclear warheads deployed on 660 intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (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 150-200 tactical nuclear warheads based in Europe.
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 September 2017, the United States Air Force deploys 399 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.
- In the 2010 Nuclear Posture Review (NPR), the Obama administration decided to “de-MIRV” the missiles, removing the second and third warhead deployed on some of the Minuteman IIIs. This process was completed in June 2014.
- Under New START, the United States plans to reduce the number of deployed ICBMs from 450 to 400. The 50 excess silos will not be destroyed but kept “warm” to accommodate missiles 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.
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 have 24 missile tubes for Trident II D5 SLBMs. Under New START, the Navy has begun to deactivate 4 tubes on each submarine; a process scheduled for completion in early 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.
- The Trident II D5 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 MIRV warhead.
- the W76-0—a 100 kt MIRV warhead.
- the W76-1—a 100 kt MIRV warhead.
- Under New START, the Navy will deploy 240 missiles armed with about 1,100 warheads.
- 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 September 2017, the Air Force deploys 38 nuclear-capable B-52H Stratofortress bombers and 11 nuclear-capable B-2A Spirit bombers.
- The Air Force will deploy no more than 60 nuclear-capable strategic bombers under New START.
- An estimated 1,038 nuclear weapons 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.
In April 2009, President Obama declared in a speech in Prague that it was the policy of the United States “to seek the peace and security of a world without nuclear weapons.” In the 2010 Nuclear Posture Review (NPR), the Obama administration announced that it “will not use or threaten to use nuclear weapons against non-nuclear weapons states that are party to the Nuclear Non-Proliferation Treaty (NPT) and in compliance with their nuclear non-proliferation obligations.” The administration reserved the right to make any adjustments to this assurance “that may be warranted by the evolution and proliferation of the biological weapons threat.” The President was not prepared to make a declaration that the “sole purpose” of its nuclear weapons was to deter a nuclear attack, but added that it would “work to establish conditions under which such a policy could be safely adopted.”
News reports indicated that the Obama administration during its last year in office considered adjusting U.S. nuclear declaratory policy to state that the United States will not be the first to use nuclear weapons in a conflict. In a January 11, 2017, speech in Washington, Vice President Joe Biden said that both he and Obama strongly believe that the sole purpose of U.S. nuclear weapons should be to deter a nuclear attack against the United States or its allies. But the President reportedly decided not to adopt a no-first-use or sole purpose policy due to concerns expressed by some members of his cabinet and close U.S. allies.
In January 2017, President Donald Trump issued an executive order calling on the Defense Department to initiate a new NPR in order to “ensure that the United States nuclear deterrent is modern, robust, flexible, resilient, ready, and appropriately tailored to deter 21st-century threats.”
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 by 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.
- 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 Nov. 30, 2014 the United States had destroyed 24,924 metric tons, or 90 percent, of its total category 1 chemical weapons stockpile. The United States has completed destruction of all its Category 2 and 3 chemical weapons.
- Due to environmental concerns requiring that materials at certain facilities be neutralized rather than incinerated, the United States does not expect to complete destruction until 2021, nine years after the Chemical Weapons Convention deadline. However, in March 2017, Conrad Whyne, chief of the Defense Department’s Program Executive Office, Assembled Chemical Weapons Alternatives, stated that all chemical weapons will be destroyed 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 2018. 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.
President Donald Trump has repeatedly criticized the agreement. During the presidential campaign, he made comments about “tearing up” the deal, although as of January 2018, he has re-issued waivers on nuclear-related sanctions on Iran to meet U.S. obligations under the agreement.
Conference on Disarmament (CD)
Established in 1979 as a multilateral disarmament negotiating forum by the international community, the United States has been a regular and active participant in the CD. 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.