| United States of America | |
|---|---|
 | |
| Nuclear program start date | 21 October 1939 |
| First nuclear weapon test | 16 July 1945 |
| First thermonuclear weapon test | 1 November 1952 |
| Last nuclear test | 23 September 1992 |
| Largest yield test | 15Mt (1 March 1954) |
| Total tests | 1,054 detonations |
| Peak stockpile | 32,040 warheads (1967) |
| Current stockpile | 3,700 total[1] (2025) |
| Current strategic arsenal | 1,770[2] (2025) |
| Cumulative strategic arsenal inmegatonnage | ≈758.9[3] (2025) |
| Maximum missile range | 13,000 km (8,078 mi) (land) 12,000 km (7,456 mi) (submarine |
| NPT party | Yes (1968, one of five recognized powers) |
TheUnited States is known to have possessed three types ofweapons of mass destruction:nuclear,chemical, andbiological weapons. The US was the first country to develop and the only country to use nuclear weapons. The 1940sManhattan Project conducted duringWorld War II led to the 1945atomic bombings of Hiroshima and Nagasaki, two cities in Japan.[4] In 1949, theSoviet Union became the secondnuclear-armed nation, prompting the United States to develop and test the firstthermonuclear weapons. As of 2025[update], the United States has thesecond-largest number of nuclear weapons in the world, after theRussian Federation (thesuccessor state to the Soviet Union).[5][6]
| Nuclear weapons |
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| Background |
| Nuclear-armed states |
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Nuclear weapons have been used twice in combat: two nuclear weapons were used by the United States against Japan duringWorld War II in theatomic bombings of Hiroshima and Nagasaki. Altogether, the two bombings killed 105,000 people and injured thousands more[7] while devastating hundreds or thousands ofmilitary bases,factories, andcottage industries.
The U.S. conducted an extensive nuclear testing program. 1054 tests were conducted between 1945 and 1992. The exact number of nuclear devices detonated is unclear because some tests involved multiple devices while a few failed to explode or were designed not to create a nuclear explosion. The last nuclear test by the United States was on September 23, 1992; the U.S. has signed but not ratified theComprehensive Nuclear-Test-Ban Treaty.
Currently, the United Statesnuclear arsenal is deployed in three areas:
The United States is one of the five "Nuclear Weapons States" under theTreaty on the Non-Proliferation of Nuclear Weapons, which the U.S. ratified in 1968. On October 13, 1999, theU.S. Senate rejected ratification of theComprehensive Test Ban Treaty, having previously ratified thePartial Test Ban Treaty in 1963. The U.S. has not, however,tested a nuclear weapon since 1992, though it has tested many non-nuclear components and has developed powerfulsupercomputers to duplicate the knowledge gained from testing without conducting the actual tests themselves.[8][9]
In the early 1990s, the U.S. stopped developing new nuclear weapons and now devotes most of its nuclear efforts intostockpile stewardship, maintaining and dismantling its now-aging arsenal.[10] The administration ofGeorge W. Bush decided in 2003 to engage in research towards a new generation of small nuclear weapons, especially "earth penetrators".[11] The budget passed by theUnited States Congress in 2004 eliminated funding for some of this research including the "bunker-busting or earth-penetrating" weapons.
The exact number of nuclear weapons possessed by the United States is difficult to determine. Different treaties and organizations have different criteria for reporting nuclear weapons, especially those held in reserve, and those being dismantled or rebuilt:
In 2002, the United States and Russia agreed in theSORT treaty to reduce their deployed stockpiles to not more than 2,200warheads each. In 2003, the U.S. rejected Russian proposals to further reduce both nation's nuclear stockpiles to 1,500 each.[14] In 2007, for the first time in 15 years, the United States built new warheads. These replaced some older warheads as part of theMinuteman III upgrade program.[15] 2007 also saw the first Minuteman III missiles removed from service as part of the drawdown. Overall, stockpiles and deployment systems continue to decline in number under the terms of theNew START treaty.
In 2014,Bulletin of the Atomic Scientists released a report, stating that there are a total of 2,530 warheads kept in reserve, and 2,120 actively deployed. Of the warheads actively deployed, the number of strategic warheads rests at 1,920 (subtracting 200 tacticalB61s as part of Nato nuclear weapon sharing arrangements). The amount of warheads being actively disabled rests at about 2,700 warheads, which brings the total United States inventory to about 7,400 warheads.[16]
The U.S. government decided not to sign the UNtreaty on the Prohibition of Nuclear Weapons, a binding agreement for negotiations for the total elimination of nuclear weapons, supported by more than 120 nations.[17]
As of early 2019, more than 90% of world's 13,865 nuclear weapons were owned by the United States and Russia. Russia has the most nuclear warheads sitting at 5,977, while the United States has 5,428 warheads.[18][19]
The U.S. Air Force currently operates 400Minuteman IIIICBMs, located primarily in the northernRocky Mountain states and theDakotas.Peacekeeper missiles were phased out of the Air Force inventory in 2005. All USAFMinuteman II missiles were destroyed in accordance with the START treaty and their launch silos imploded and buried then sold to the public under theSTART II. The U.S. goal under the SORT treaty was to reduce from 1,600 warheads deployed on over 500 missiles in 2003 to 500 warheads on 450 missiles in 2012. The first Minuteman III were removed under this plan in 2007 while, at the same time, the warheads deployed on Minuteman IIIs began to be upgraded from smallerW62s to largerW87s from decommissioned Peacekeeper missiles.[15]
The U.S. Air Force also operates a strategic nuclear bomber fleet. The bomber force consists of 51 nuclear-armedB-52 Stratofortresses, and 20B-2 Spirits.[20] All 64B-1s were retrofitted to operate in a solely conventional mode by 2007 and thus don't count as nuclear platforms.
In addition to this, the U.S. military can also deploy smallertactical nuclear weapons either throughcruise missiles or with conventionalfighter-bombers. The U.S. maintains about 400 nucleargravity bombs capable of use by theF/A-18 Hornet,F-15E,F-16,F-22 andF-35.[15] Some 350 of these bombs are deployed at seven airbases in six European NATO countries;[15] of these, 180 tacticalB61 nuclear bombs fall under anuclear sharing arrangement.[21]
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TheU.S. Navy currently has 18Ohio-classsubmarines deployed, of which 14 areballistic missile submarines. Each submarine is equipped with a maximum complement of 24Trident II missiles. Approximately 12 U.S.attack submarines were equipped to launch nuclearTomahawk missiles, but these weapons were removed from service by 2013.[22]
The number of Deployed and Non-Deployed SLBMs on the Ohio-Class SSBNs as of 2018[update] is 280, of which 203 SLBMs are deployed.[20]
The United States offensive biological weapons program was instigated by PresidentFranklin Roosevelt and theU.S. Secretary of War in October 1941.[23] Research occurred at several sites. A production facility was built atTerre Haute, Indiana, but testing with a benign agent demonstrated contamination of the facility so no production occurred duringWorld War II.[24]
The US government and military is known for using civilian populations to test the effects of bioweapons. In 1950, the US Navy conducted a secret experiment on the civilian population of theSan Francisco Bay Area during operationOperation Sea-Spray, in which over 800,000 residents were unknowingly sprayed with pathogens. This led to at least one death and claims that the ecology had been changed irreversibly.[25]
In 1951, the US military also released fungal spores at theNorfolk Naval Supply Center onAfrican-American workers to see if they are more susceptible to the pathogen than Caucasians.[26] In 1966, the US government releasedBacillus globigii on theNew York Subway to research how a civilian population can be used to spread pathogens. It is claimed many of those exposed were later found to exhibit long-term medical conditions of which the military has denied causation.[26]
The US government continued similar experiments on civilian populations in other cities across the country until the early 1970s.
TheDugway Proving Ground facility inUtah, opened in 1942, to this day tests and stores biological weapons. The 800,000 acre facility has reportedly weaponized fleas, mosquitoes, as well as conducted experiments on both animal and human subjects.[27]
A more advanced production facility was constructed inPine Bluff, Arkansas, which began producing biological agents in 1954.Fort Detrick,Maryland, later became a production facility as well as a research site. The U.S. developed anti-personnel and anti-crop biological weapons.[28] Several deployment systems were developed including aerial spray tanks, aerosol spray canisters, grenades, rocket warheads and cluster bombs. (See alsoU.S. Biological Weapon Testing)
In mid-1969, the UK and the Warsaw Pact, separately, introduced proposals to the UN to ban biological weapons, which would lead to a treaty in 1972. The U.S. cancelled its offensive biological weapons program byexecutive order in November 1969 (microorganisms) and February 1970 (toxins) and ordered the destruction of all offensive biological weapons, which occurred between May 1971 and February 1973. The U.S. ratified theGeneva Protocol on January 22, 1975. The U.S. ratified theBiological Weapons Convention (BWC) which came into effect in March 1975.[Kissinger 1969]
Negotiations for a legally binding verification protocol to the BWC proceeded for years. In 2001, negotiations ended when theBush administration rejected an effort by other signatories to create a protocol for verification, arguing that it could be abused to interfere with legitimate biological research.
TheU.S. Army Medical Research Institute of Infectious Diseases, located in Fort Detrick, produces small quantities of biological agents, for use in biological weapons defense research. According to the U.S. government, this research is performed in full accordance with the BWC.
In September 2001, shortly after theSeptember 11 attacks on the United States, there was a series ofanthrax attacks aimed at U.S. media offices and the U.S. Senate which killed five people. The anthrax used in the attacks was theAmes strain, which was first studied at Fort Detrick and then distributed to other labs around the world.
InWorld War I, the U.S. had its own chemical weapons program, which produced its own chemical munitions, includingphosgene andmustard gas.[29] The U.S. only created about 4% of the total chemical weapons produced for that war and just over 1% of the era's most effective weapon, mustard gas. (U.S. troops suffered less than 6% of gas casualties.) Although the U.S. had begun a large-scale production ofLewisite, for use in an offensive planned for early 1919, Lewisite was not deployed during World War I.[30][31] The United States also created a special unit, the 1st Gas Regiment,[29] which used phosgene in attacks after being deployed to France.[32]
Chemical weapons were not used by theAllies or Germany duringWorld War II for military purposes, but such weapons were deployed to Europe from the United States. In 1943, German bombers attacked the port ofBari in Southern Italy, sinking several American ships – among themJohn Harvey, which was carrying mustard gas. The presence of the gas was highly classified, and, according to the U.S. military account, "Sixty-nine deaths were attributed in whole or in part to the mustard gas, most of them American merchant seamen" out of 628 mustard gas military casualties.[Navy 2006][Niderost] The affair was kept secret at the time and for many years. After the war, the U.S. both participated in arms control talks involving chemical weapons and continued tostockpile them, eventually exceeding 30,000 tons of material.
After the war, all of the former Allies pursued further research on the three newnerve agents developed by the Nazis:tabun,sarin, andsoman. Over the following decades, thousands of American military volunteers were exposed to chemical agents duringCold War testing programs, as well as in accidents. (In 1968, one such accident killed approximately 6,400 sheep when an agent drifted out ofDugway Proving Ground during a test.[33]) The U.S. also investigated a wide range of possible nonlethal, psychobehavioral chemical incapacitating agents includingpsychedelicindoles such asLSD andmarijuana derivatives, as well as several glycolate anticholinergics. One of the anticholinergic compounds,3-quinuclidinyl benzilate, was assigned theNATO code BZ and was weaponized at the beginning of the 1960s for possible battlefield use. Alleged use of chemical agents by the U.S. in theKorean (1950–53) conflict has never been substantiated.[34][35][36]
In late 1969, PresidentRichard Nixon unilaterally renounced the first use of chemical weapons (as well as all methods of biological warfare).[37] He issued a unilateral decree halting production and transport of chemical weapons which remains in effect. From 1967 to 1970 inOperation CHASE, the U.S. disposed of chemical weapons by sinking ships laden with the weapons in the deepAtlantic. The U.S. began to research safer disposal methods for chemical weapons in the 1970s, destroying several thousand tons of mustard gas by incineration and nearly 4,200 tons of nerve agent by chemical neutralization.[38]
The U.S. entered theGeneva Protocol in 1975 (the same time it ratified theBiological Weapons Convention). This was the first operative international treaty on chemical weapons to which the U.S. was party. Stockpile reductions began in the 1980s, with the removal of some outdated munitions and destruction of the entire stock of BZ beginning in 1988. In 1990, destruction of chemical agents stored onJohnston Atoll in thePacific began, seven years before theChemical Weapons Convention (CWC) came into effect. In 1986, PresidentRonald Reagan began removal of the U.S. stockpile of chemical weapons from Germany[39] (seeOperation Steel Box).In 1991, PresidentGeorge H. W. Bush unilaterally committed the U.S. to destroying all chemical weapons and renounced the right to chemical weapon retaliation.
In 1993, the U.S. signed the CWC, which required the destruction of all chemical weapon agents, dispersal systems, chemical weapons production facilities by 2012. Both Russia and U.S. missed the CWC's extended deadline of April 2012 to destroy all of their chemical weapons.[40] The United States destroyed 89.75% of the original stockpile of nearly 31,100metric tons (30,609long tons) of nerve and mustard agents under the terms of the treaty.[41] Chemical weapons destruction resumed in 2015.[42] The country's last stockpile was at theBlue Grass Army Depot in Kentucky.[43] The U.S. destroyed its final chemical weapon on July 7, 2023.[44] The final weapon to be destroyed was asarin nerve agent-filledM55 rocket. The total cost for the program to destroy chemical weapons was $40 billion.[45]
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