Nuclear
The United States used nuclear weapons on Hiroshima and Nagasaki in August 1945, making it the only country that has ever used nuclear weapons during a conflict. As one of the five recognized nuclear weapons states under the Nuclear Non-Proliferation Treaty (NPT), the United States maintains a sizeable arsenal of nearly 10,000 nuclear warheads, of which nearly 6,000 are operational and the remainder in reserve or inactive stockpiles.  Approximately 1,700 warheads are deployed on land-based missile systems, 1,098 on bombers, and 3,168 on submarines (Ohio-class submarines). Approximately 800 are tactical nuclear weapons (TNWs), and consist of Tomahawk land attack cruise missiles and B61 bombs. The remaining warheads are stockpiled. 

The United States deploys nuclear weapons at eight bases in six European NATO countries. According to the May 2002 Treaty of Moscow (the Strategic Offensive Reductions Treaty, or SORT) between the United States and the Russian Federation, both countries are required to reduce their strategic nuclear arsenals to 1,700-2,200 operationally deployed warheads by 2012.

In October 1999, the U.S. Senate voted not to ratify the Comprehensive Nuclear Test Ban Treaty. The current Bush Administration's position on the CTBT is that while it has no plans to seek reconsideration of the Senate's refusal to ratify, it intends to maintain its moratorium on nuclear testing in place since 1992.

The Bush administration in early 2007, proposed combining elements of two designs from Los Alamos and Laurence Livermore National Laboratory to upgrade the US nuclear arsenal. The new weapons would replace the nation’s existing arsenal of aging warheads, with the new weapons designed to be sturdier, more reliable, safer from accidental detonation and more secure from theft by terrorists. The proposal is estimated at over $100 billion. Furthermore, the current schedule, which is flexible, requires the president to make a decision within the next two years and, if approved, to begin development by fiscal year 2010 and production by 2012.

Biological
The U.S. offensive biological warfare (BW) program was launched in 1943 and terminated in 1969, by executive order. During this period, the U.S. weaponized a variety of pathogens and toxins for use against humans and plants. The anti-human agents it developed for weapons purposes were Bacillus anthracis (anthrax), Francisella tularensis (tularemia), Coxiella burnetii (Q fever), the Venezuelan equine encephalitis virus, and staphylococcal enterotoxin B. The anti-plant agents were the fungi that cause wheat rust and rice blast. In addition, U.S. military scientists conducted research on pathogens that cause smallpox, glanders, and plague, as well as several toxins, such as botulinum toxin, saxitoxin, and ricin. The entire U.S. BW stockpile was destroyed in 1969 and 1970; since that time, it has not had an offensive BW program. The U.S. ratified the Biological and Toxins Weapons Convention (BWC) in March 1975 and had an important role in the process of developing confidence-building measures (CBMs) during several BWC review conferences. However, in 2001, the Bush administration rejected an effort by other signatories to conclude a protocol that would provide verification measures. Since then, the remaining parties to the BWC have conducted semiannual meetings to discuss, among other things, national measures for the implementation of biosecurity regulations and penal legislation, leading up to the Sixth Review Conference in 2006.[2] In addition, the United States has conducted an active biodefense program for many years in accordance with BWC provisions that permit the use of agents of types and in quantities appropriate for prophylactic, protective, or other peaceful purposes. These activities are reported each year to Congress and in an annual information exchange on biodefense activities under the BWC. A 4 September 2001 New York Times article identified previously undisclosed U.S. government biodefense projects involving a model of a germ bomb, a factory to make biological agents, and the development of more potent anthrax. The United States denied allegations that this research was anything other than defensive in nature and asserted that it did not violate any BWC provisions or CBMs. On 28 April 2004, President Bush outlined the administration's perspective on biological weapons by issuing National Security Presidential Directive (NSPD-33) called "Biodefense for the 21st Century", an initiative to strengthen the country's biodefense capabilities through programs in threat awareness, prevention and protection, surveillance and detection, and response and recovery. The Bush administration also faces criticism that financial resources have been redirected from non-biodefense research in order to fund additional biodefense research.
 

Chemical
The U.S. chemical warfare (CW) program began with the establishment of the Chemical Warfare Service in June 1918. During World War I, the United States manufactured, stockpiled, and used chemical weapons. Chemical weapons development and production continued during and after World War II, but the production of unitary chemical munitions was terminated in 1969. During the Reagan administration, the production of binary chemical weapons was restarted, but was discontinued in 1990. Since then, the United States no longer has an active CW program. The United States ratified the Geneva Protocol in 1975, with the reservation that the treaty not apply to defoliants and riot control agents such as were used in Vietnam and Laos during the Vietnam War. Currently, the United States has what is believed to be the world's second largest stockpile of chemical weapons, including bombs, rockets, and artillery shells that are loaded with lewisite, mustard, sarin, soman, VX, or binary nerve agents. According to the U.S. Army Chemical Materials Agency, as of 29 November 2006, the United States has destroyed 41% of its original stockpile of 27,768 metric tons of declared chemical agents. Under terms of the Chemical Weapons Convention (CWC), which the United States ratified in April 1997, the United States committed to destroying all chemical stockpiles by April 2007. However in April 2006, Washington requested an extension to April 2012, the final deadline set by the CWC, citing delays in initiating operations and lower-than-planned destruction rates at chemical weapons destruction facilities. U.S. media, citing Pentagon documents, reported in November 2006 that the United States plans to extend its timeline to destroy its chemical weapons arsenal until 2023.
 

Missile
The United States has the capability to produce highly sophisticated liquid- and solid-fueled missiles of all ranges. It currently deploys 500 Minuteman and 10 MX/Peacekeeper nuclear-tipped intercontinental ballistic missiles (ICBMs) at three bases in Montana, North Dakota, and Wyoming. The number of warheads on Minuteman missiles was scheduled to be reduced from three to one by 2007 under the defunct START II agreement, but this plan may be revised to assign between 700 to 800 warheads to the 500 Minutemen missiles. Deactivation of the MX/Peacekeeper force began in October 2002 and will conclude in 2005, at the cost of $600 million. In 2004, the Defense Department retired 17 additional MX/Peacekeeper missiles as part of this plan, and the final 10 MX missiles will be withdrawn from alert status by October 1, 2005. These remaining missiles will not be destroyed as prescribed under START II, but will be retained as stipulated in the 2001 NPR for potential use as space launch vehicles, target vehicles, or for redeployment. The Minuteman missile force is also undergoing a $6.0 billion modernization program to improve the weapon's accuracy, reliability, and to extend its service life beyond 2020. A new, longer-range ICBM, to be ready in 2018, is being considered by the Pentagon. As of early 2005, the U.S. Navy had 14 operational Ohio-class nuclear-powered ballistic missile submarines (SSBN), having reduced its level by one in 2004 to meet NPR specifications. The four oldest subs in the original class of 18 have been converted to carry non-nuclear cruise missiles. The 14 operational SSBNs carry a total of 336 Trident-1 and Trident-II submarine-launched ballistic missiles (SLBM), each carrying between six and eight warheads, for an estimated total of 2,016. All SSBNs will be modified to carry the Trident II missiles, and the navy has extended the service life of the Trident-II from 30 to 49 years. The Pentagon is planning to introduce a new SSBN in 2029 when the oldest of the current subs will be retired. Previous predictions indicated that the U.S. Navy would station the 14 SSBNs evenly among the Atlantic and Pacific fleets; however, recent planning shifts have called for an SSBN fleet of 9 to be stationed in the Pacific with only 5 submarines in the Atlantic. Also, in 2004, the Navy initiated the Enhanced Effectiveness (E2) Reentry Body Program that would allow missiles to be targeted within 10-meter accuracy, expanding the list of potential targets to be attacked by W76 warheads. Finally, the Navy plans to resume SLBM flight tests in 2005 and plans to develop a submarine-launched intermediate-range ballistic missile (SLIRBM) that would carry nuclear and conventional payloads. The U.S. bomber force consists of 94 B-52 bombers stationed at Barksdale AFB in Louisiana and Minot AFB in North Dakota, and 21 B-2 bombers stationed at Whiteman Air Force Base, Missouri. The B-52 can deliver air-launched cruise missiles (ALCM), advanced cruise missiles (ACM), or gravity bombs. The B-2 carries only gravity bombs. It is estimated that 450 ALCMs are deployed as well as around 400 operational ACMs, which have a longer range, greater accuracy, and more difficult to intercept than an ALCM. The B-2s are scheduled to undergo upgrades allowing them to make mission and target changes in route. The U.S. Air Force intends to expedite the process of finding a replacement for its current bomber force, considering long- and mid-range options, unmanned aircraft, and new bombers. The United States is a member of the Missile Technology Control Regime (MTCR), whose goal is to control the transfer of nuclear-capable missiles and unmanned delivery systems capable of carrying all types of WMD.
 

	Updated November 2006