This is a history of Iran's efforts to develop chemical weapons. The emphasis is on Iran's technical achievements rather than its motives, and the essay relies primarily on statements and reports produced by government agencies and international organizations. The essay describes the origins of Iran's chemical weapon (CW) program during the Iran-Iraq war, Iran's efforts to establish an indigenous CW production capability through foreign procurement, its CW-related transfers, and its adherence to the Chemical Weapons Convention (CWC).

In 1997, the U.S. Central Intelligence Agency (CIA) publicly reported that Iran had manufactured and stockpiled blister, blood, and choking agents, and had bombs and artillery shells needed to deliver these agents.[1] Subsequent U.S. intelligence reports expanded on these findings, alleging the production and stockpiling of nerve agents and describing Iran's failure to declare its CW production facilities and past CW-related transfers.[2] In 2005, the United States judged Iran to be in violation of its CWC commitments.[3] This finding was softened in subsequent U.S. government reports and testimony, which cited an inability to certify Iran's compliance. Then, in 2018, the United States certified Iran in non-compliance with the CWC, a finding it reaffirmed in 2019.[4]  

Information about Iran's foreign suppliers of CW precursors and expertise is derived largely from U.S. sanctions actions since the late 1990s. Entities in China, India, and Russia have been among Iran's primary suppliers.

Early Development during the Iran-Iraq War

In September 1980, Iraqi troops invaded Iran, triggering a war that would last until August 1988.[5] During the early years of the conflict, Iran refrained from using chemical weapons against Iraq, reportedly because Supreme Leader Ayatollah Ruhollah Khomeini objected to their use.[6] However, according to the U.S. Defense Intelligence Agency (DIA), Iran initiated a chemical weapon development program in 1983 "in response to Iraqi use of riot control and toxic chemical agents."[7] By 1998, the Iranian government had publicly acknowledged that it began a CW program during the war.[8] According to the DIA, the program began under the Islamic Revolutionary Guard Corps (IRGC), with the role of the Ministry of Defense increasing over time.[9]

In April 1984, the Iranian delegate to the United Nations, Rajai Khorassani, admitted at a London news conference that Iran was "capable of manufacturing chemical weapons [and would] consider using them."[10] In 1987, according to the U.S. Department of Defense, Iran was able to deploy limited quantities of mustard gas (a blister agent) and cyanide (a blood agent) against Iraqi troops.[11] The change in Iran's policy with regard to chemical warfare was publicly announced in December 1987, when Iranian Prime Minister Hussein Musavi reportedly told parliament that Iran was producing "sophisticated offensive chemical weapons."[12]

As Iran's chemical warfare capabilities grew, it became more difficult to determine which side was responsible for chemical attacks during the Iran-Iraq war. In March 1988, the Kurdish town of Halabja in northern Iraq was caught in chemical weapon crossfire between Iranian and Iraqi forces that left thousands of civilians dead. A 1990 U.S. Department of Defense reconstruction of the incident reportedly concluded that both Iran and Iraq used CW in Halabja. Iran allegedly attacked the town with cyanide gas bombs and artillery, and Iraqi forces allegedly used a mixture of mustard gas and nerve agents. In total, the Defense Department study reportedly estimated that Iranian forces used more than 50 chemical bombs and artillery shells during the offensive. [13]

Iran appears to have developed additional chemical warfare agents. In April 1987, Iran is believed to have used mustard-filled 130 mm mortars near Basrah, Iraq.[14] In April 1988, a U.N. medical specialist examined several dozen Iraqi soldiers and concluded that they could have been exposed to mustard gas.[15] Iraq turned over 141 chemical weapon mortar rounds to the United Nations, claiming that they were Iranian-origin. Analysis of samples from these rounds by specialized laboratories in Switzerland and Sweden revealed the presence of mustard gas, according to a July 1988 U.N report.[16] A 1991 inspection at Iraq's Muthana State Establishment by the United Nations Special Commission (UNSCOM) also found 165 81-mm mortars filled with sulfur mustard that Iraq claimed were Iranian-origin. [17]

U.N. and U.S. government reports also indicate that Iran may have used nerve and choking agents. The April 1988 U.N. medical specialist observed symptoms in Iraqi soldiers that indicated possible exposure to "an acetylcholine esterase-inhibiting chemical in small concentrations," which could suggest the use of a nerve agent.[18] In addition,  a 1990 DIA study reported that a "U.N. team that examined Iraqi casualties from Iranian chemical attacks found that some of them displayed the effects of exposure to a choking agent believed to have been phosgene."[19]

Finally,during the 2003 invasion of Iraq, U.S. forces discovered Iraqi intelligence reports indicating that Iran had used chemical weapons during the Iran-Iraq War.[20] Despite these findings, Iran has failed to acknowledge that it used chemical weapons.

Post-War Developments and Intelligence Assessments

Although Iran claims that it terminated its chemical weapon program after the Iran-Iraq war,[21] the United States believes that Tehran continued and perhaps accelerated its effort to develop, stockpile, and weaponize chemical agents after the 1988 cease-fire.[22] In February 1997, Director of Central Intelligence George Tenet named Iran as one of approximately twenty countries that either had or were developing chemical and biological weapons. Tenet characterized Iran's chemical weapon program at the time as "increasingly active."[23] In March 2001, General Tommy Franks, head of U.S. Central Command, testified before the U.S. House Armed Services Committee that Iran was "the holder of the largest chemical weapons stockpile" in his area of responsibility.[24] U.S. intelligence assessments at the time put Iran's stockpile of chemical agents at anywhere from several hundred to several thousand metric tons.[25]

In a series of reports to Congress beginning in 1997, the CIA asserted that Iran had made and was stockpiling blister, blood, and choking agents and was seeking equipment and expertise – mostly from China – to "create a more advanced and self-sufficient CW infrastructure."[26] In September 2000, the CIA assessed that Iran's chemical weapon program still relied upon external suppliers for technology, equipment and precursor chemicals, but that Tehran was "rapidly approaching self-sufficiency and could become a supplier of CW-related materials to other nations."[27] In 2001, the CIA reported that Iran's CW-related foreign procurement was also aimed at "having an indigenous nerve agent production capability"[28] and the following year reported that Iran "probably also has made some nerve agents."[29] By the second half of 2003, the CIA reported that Iran was seeking "production technology, training and expertise" that could help it "achieve an indigenous capability to produce nerve agents."[30]

U.S. concern about Iran's CW capability appears to have shifted in the mid-2000s. At this point, U.S. intelligence reports characterized the nature and size of Iran's capability as historic and modest in scope rather than active and expansive.

In December 2006, the U.S. Director of National Intelligence judged that Iran "maintains a Chemical Warfare (CW) research and development program" and "a small, covert CW stockpile."[31] In 2007, the U.S. Director of National Intelligence assessed that Iran "maintains the capability to produce CW agent in times of need and conducts research that may have offensive applications."[32]

U.S. and foreign government reports indicate that CW-related research and development was carried out at Iranian universities in order to avoid detection. According to a 2005 report from Germany's Customs Office of Criminal Investigations (ZKA), Iran used small, well-guarded university laboratories for CW-related research and that Iran probably possesses sulfur mustard, tabun, and prussic acid (hydrogen cyanide), and may possess the nerve agents sarin and VX.[33] In April 2019, the U.S. State Department reaffirmed this assessment, reporting that Iran's military-controlled Imam Hossein University (IHU) and Malek Ashtar University (MUT) have been researching "chemical agents intended to incapacitate" since 2005. According to this report, IHU's Chemistry Department also sought "kilogram quantities" of medetomidine from Chinese suppliers in 2014, which the Department has researched as an incapacitant.[34]

U.S. concerns that Iran had an active, undeclared CW program were publicly revived in 2015. In a State Department report that year, the United States questioned whether Iran "has fully declared those chemicals it holds for riot-control purposes."[35] In 2019, U.S. intelligence determined that Iran had failed to declare its stockpile of dibenzoxazepine (CR) gas as a riot control agent, citing delivery devices such as a personal defense spray advertised by the Iranian Ministry of Defense. Iran's Shahid Meisami Group (SMG) has marketed riot control agents at defense exhibitions, including an "Ashkan" irritant hand grenade that can produce CR smoke and a "Fog Maker System" that can disseminate chemicals over a large area. The report also noted "serious concerns" that Iran is currently developing offensive pharmaceutical-based agents (PBAs).[36]

Iran and the Chemical Weapons Convention

Iran became a State Party to the Chemical Weapons Convention (CWC) on December 3, 1997.[37] As a member, Iran is prohibited from developing, producing or stockpiling chemical weapons. Since ratifying the CWC, Iran has been active within the Organisation for the Prohibition of Chemical Weapons (OPCW), the international agency responsible for promoting and administering the CWC. In December 2000, the OPCW Director-General publicly stated that the OPCW had "no reason whatsoever to question Iran's full compliance with the CWC," and that verification measures in Iran were "strictly in accordance with the Convention."[38]

During its participation in the OPCW, Iran has frequently asserted its commitment to the CWC. For example, in April 2003, the Iranian delegate to the OPCW acknowledged that Iran had developed "chemical capabilities" during the last phase of the Iran-Iraq war but claimed that Iran never used these weapons and dismantled them after the cease-fire. In addition, the delegate stated that Iran destroyed its chemical weapon facilities under the supervision of OPCW inspectors and received certification of destruction. He cited these actions as "clear proof of [Iran's] full commitment and compliance" to the CWC. [39] In October 2003, Iran reiterated that it was "fully committed to the implementation of the Convention and total elimination of all weapons of mass destruction" and had "submitted all required declarations."[40]

Despite these assertions, some states have questioned Iran's compliance, as well as its motives for participating in the CWC. Israel has alleged that Iran is using its membership in the OPCW to mask efforts to acquire chemical weapon materials and technology. In June 2002, the director of Israel's Mossad intelligence service was quoted as saying that Iran's adherence to the CWC was only "a cover for the construction of a dual-purpose civilian infrastructure which could be converted very speedily into production capabilities of large quantities of VX [gas]."[41]

The United States has also scrutinized Iran's commitment to its CWC obligations. A 2003 State Department report judged that Iran had not submitted "a complete and accurate declaration" of its chemical weapons program and was, in fact, "acting to retain and modernize key elements" of the program."[42] In 2005, the State Department judged Iran "in violation of its CWC obligations" because of its efforts to "retain and modernize key elements of its CW infrastructure," including an offensive CW R&D capability and dispersed mobilization facilities.[43]

Subsequent State Department reports were less conclusive. From 2010 to 2018, the United States was unable to certify Iran's compliance with the CWC because of "irregularities in the Iranian declaration and insufficient clarification from Iran." In particular, the United States was concerned that Iran retained an undeclared CW stockpile and was unable to certify that Iran had accurately declared its chemical weapon production infrastructure and its CW-related transfers.[44] U.S. concerns about the transfer of CW munitions to Libya in the late 1980s were first reported in 2012,[45] while concerns about the accuracy of Iran's declaration related to riot-control agents emerged in 2015.[46]

By 2018, the United States determined that Iran was in "noncompliance with its obligations under the Chemical Weapons Convention."[47] The State Department report published in April 2019 described the justification for this finding, including Iran's transfer of chemical weapons to Libya during the 1978-1987 Libya-Chad War, Iran's failure to declare its complete stockpile of riot control agents (RCAs), and its failure to fully declare CW production facilities.[48]

Proliferation

Over the last decade, U.S. government reports have offered increased clarity on Iran's alleged transfers of chemical weapons to Libya during the 1980s and technical support for Syria's chemical weapons program during the 2000s.

Libya

Iran may have provided Libya with chemical weapons during the Iran-Iraq War. In 1987, media reports alleged that Iran had transferred chemical weapons to Libya in exchange for Soviet-made mines and that Libya had attempted to use these weapons in its war with Chad.[49] A 1995 U.S. Department of Defense report appeared to confirm these allegations, stating that "Iran supplied the [chemical] agents in exchange for naval mines."[50] Following the 2011 civil war in Libya, the Libyan transition government informed the OPCW that its fighters had discovered 517 130mm artillery shells and 8 aerial bombs containing 1.3 metric tons of sulfur mustard gas in cases with Persian markings. The United States assessed that these previously undisclosed chemical weapons originated from Iran during the 1980s.[51]

Syria

Iran has allegedly supported Syria's chemical weapons program. In 2006, U.S. diplomats reportedly indicated that Iran planned to assist Syria in the construction of chemical weapons facilities for the production of "tens to hundreds of tons of precursors for VX, sarin, and mustard [gas]." Engineers from Iran's Defense Industries Organization (DIO) allegedly planned to visit Syria and construction was scheduled to take place from 2005 to 2006.[52] German intelligence has also reported Iranian cooperation with Syria's Scientific Studies and Research Centre (SSRC), a Syrian government agency responsible for developing chemical weapons and ballistic missiles.[53]

Foreign Suppliers

Foreign assistance has been vital to Iran's chemical weapon effort. Firms in China, India, and Russia have been Iran's primary suppliers of chemical equipment and precursor chemicals. Companies in Germany, Israel, and the United States have also been involved.

U.S. government reports and intelligence assessments emphasized the value and volume of foreign assistance beginning in the 1990s. Examples of CW-related assistance are also available in U.S. sanctions actions, often taken by the State Department pursuant to the Iran Nonproliferation Act (now the Iran, North Korea, Syria Nonproliferation Action, or INKSNA). However, sanctions under INKSNA are comparatively mild for firms without a presence in the United States. Penalties apply for only two years and include a ban the U.S. government from procuring from, contracting with, providing assistance to, or issuing export licenses involving controlled items for the entity.

China

According to the CIA, Chinese entities have been among the most active suppliers of CW-related equipment and technology.[54] Iran has obtained precursor chemicals, glass-lined vessels, and special air filtration equipment – all of which can be used in the production of chemical agents – from Chinese firms. Iran has also purchased Chinese technology that would enable it to manufacture such chemical weapon production equipment on its own.[55]

In 1995, the State Department sanctioned three Hong Kong-based companies for supplying Iran with precursors for mustard gas and sarin.[56] Several months later an Austrian and German firm were also sanctioned for CW-related transfers to Iran.[57] In May 1997, the State Department sanctioned one Hong Kong company, two Chinese companies and five Chinese individuals for "knowingly and materially contributing to Iran's chemical weapons program." These entities and persons were "involved in the export of dual-use chemical precursors and/or chemical production equipment and technology." [58] One of the Chinese companies, Jiangsu Yongli Chemicals and Technology Import and Export Corporation, reportedly helped Iran build a plant for manufacturing dual-use chemical weapon equipment. Jiangsu Yongli was sanctioned again in June 2001, reportedly for enabling the Iranians to get the facility "up and running."[59]

One of the Chinese individuals sanctioned in May 1997, Chen Qingchang (also known as Q.C. Chen), has been a target of U.S. sanctions since then.[60] In a March 2005 address, U.S. Assistant Secretary of State for Arms Control Stephen Rademaker expressed concern that "the Chinese authorities have been unable to halt the proliferation activities of Q.C. Chen who has repeatedly provided material support to the Iranian chemical weapons program."[61]

In 1998, a branch of SinoChem Corp. reportedly supplied Iran with 500 tons of phosphorus pentasulphide, a precursor for nerve agents.[62]  In 2002, the State Department sanctioned China Machinery and Equipment Import Export Corporation for "chemical weapons proliferation activities" involving Iran.[63] Zibo Chemical Equipment Plant, a firm in China capable of manufacturing large-size glass-lined chemical equipment, has been repeatedly sanctioned for proliferation activities with Iran, most recently in 2011.[64] There have been fewer instances of U.S. sanctions targeting Chinese entities for CW-related transfers to Iran since that time.

In rare cases, Chinese authorities have cooperated with the United States to prevent the proliferation of CW-related materials to Iran. In June 2006, customs officials stopped a shipment of 2,000 kg of potassium bifluoride, which can be used to manufacture nerve agents, to Iran. Chinese authorities reportedly received a tip from the U.S. Embassy in Beijing to intercept the shipment. [65]

India

Indian firms have also helped Iran build its chemical weapon infrastructure. In March 1989, the State Trading Corporation, an Indian government trading company, reportedly sold Iran 60 tons of thionyl chloride, a precursor chemical that can be used to produce mustard gas. The State Trading Company may have purchased the chemicals from Transpek, a private Indian chemical company. [66] According to a classified German intelligence report cited by the Washington Times in 1995, at least three Indian companies aided Iran in the construction of a secret CW complex. The report projected that Iran was only months away from completing the plant, which the Indian companies claimed was a pesticide factory.[67]

The U.S. intelligence community last identified India as one of Iran's primary suppliers of CW-related material during the second half of 1996.[68]. Nevertheless, the United States has occasionally sanctioned Indian companies for CW-related proliferation to Iran. In December 2005, Sabero Organic Chemicals Gujarat and Sandhya Organic Chemicals were sanctioned for the export of phosphorus oxychloride and trimethyl phosphite to Iran, both of which can be used in the manufacture of chemical weapons.[69] In August 2006, the United States sanctioned Balaji Amines and Prachi Poly Products for supplying precursor chemicals to Iran.[70]

Russia

Russian entities have also been active suppliers to Iran of CW-related equipment and technology. In June 1999, the CIA reported that Iran had sought "production technology, expertise, and chemicals that could be used as precursor agents in its chemical warfare (CW) program from entities in Russia and China."[71] In October 2000, a senior CIA official reported that "numerous Russian entities have been providing Iran with dual-use industrial chemicals, equipment, and chemical production technology that could be diverted to Tehran's offensive CW program." The official specifically mentioned that in 1999 "Russian entities provided production technology, training, and expertise that Iran could use to create a more advanced and self-sufficient CW infrastructure."[72]

The U.S. intelligence community last identified Russia as a primary supplier of CW-related materials to Iran in 2001.[73]

Other Countries

Firms in other countries have also assisted Iran with the acquisition of precursor chemicals and CW-related equipment and expertise. For example, during 1987 and 1988, an Iranian diplomat reportedly arranged for a West German company to purchase 210 tons of thiodiglycol – a mustard gas precursor – from a supplier in the United States and then ship it to Iran in three installments, routing the shipments through Greece and Singapore to conceal their true destination. Reportedly, two shipments totaling 90 tons successfully made it to Iran, while the third 120-ton shipment was intercepted by U.S. customs agents.[74] Alcolac International, the U.S. firm, pleaded guilty to selling the thiodiglycol "with knowledge or reason to know" that the chemical was not intended for its designated destination, Singapore.[75]

Iran has made other attempts to procure U.S.-origin materials with CW applications. In 1997, U.S. authorities thwarted a conspiracy led by Iranian national Abdol Hamid Rashidian and American national Henry Joseph Trojack to ship impregnated alumina from the United States to Iran via the United Arab Emirates.[76] This material may be used in the production of nerve agents. In 1998, a court in Israel convicted Nahum Manbar, an Israeli citizen, of selling 150 tons of chemical weapon materials to Iran between 1990 and 1995.[77] Manbar reportedly also provided Iran with know-how and a list of equipment necessary to build factories to produce mustard gas and the nerve agents tabun, sarin, and soman.[78] He had been sanctioned in 1994 by the United States for CW proliferation activities and remains subject to U.S. sanctions.[79]

In 2003, the South African government prosecuted the company African Amines for exporting 120 tons of the tabun nerve agent precursor dimethylamine to Iran.[80]