A History of Iran’s Chemical Weapon-Related Efforts

This is a brief 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 program during the Iran-Iraq war, and Iran’s more recent efforts to acquire chemicals and technology in order to establish an indigenous production capability. Despite Iran’s adherence to the Chemical Weapons Convention, U.S. intelligence agencies believe that Iran maintains a chemical arsenal that probably includes blister, blood and choking agents and possibly nerve agents. Iran’s primary foreign suppliers of chemical weapon precursors and expertise have included China, Russia and India.

Early Development during the Iran-Iraq War

In September 1980, Iraqi troops invaded Iran, triggering a war that would last until August 1988. During the early years of the conflict, Iran refrained from using chemical weapons against Iraq, reportedly because spiritual leader Ayatollah Ruhollah Khomeini objected to their use. 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” during the war. By 1998, the Iranian government had publicly acknowledged that it began a chemical weapon program during the war. 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. The IRGC, or Pasdaran, is separate from Iran’s regular army. It was established by the revolutionary government to handle internal security functions. U.S. officials credit Iran’s Defense Industries Organization, a part of the Ministry of Defense, with assembling the various elements of Iran’s chemical arms effort.

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.” In 1987, according to the U.S. Department of Defense, Iran was able to deploy limited quantities of mustard gas and cyanide against Iraqi troops. The change in Iran’s policy with regard to chemical warfare was publicly announced in December 1987, when Iranian Prime Minister Hussein Musavi was reported to have told parliament that Iran was producing “sophisticated offensive chemical weapons.”

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, sandwiched between Iranian and Iraqi forces, was caught in chemical weapon crossfire that left thousands of civilians dead. A 1990 U.S. Department of Defense reconstruction of the Halabja incident reportedly concluded that both Iran and Iraq used chemical weapons 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 estimated that Iranian forces used more than 50 chemical bombs and artillery shells during the offensive. The Pentagon analysis of the Halabja incident is corroborated by a 1990 report co-written by Stephen Pelletiere, the CIA’s senior political analyst on Iraq during the Iran-Iraq war. In his report, Pelletiere stated that there was “no evidence whatsoever that the Iraqis have ever employed blood gasses such as cyanogen chloride or hydrogen cyanide.” Because “blood agents were allegedly responsible for the killing of Kurds at Halabjah,” Pelletiere concluded that “the Iranians perpetrated this attack.”

According to some reports, Iran may have used still other chemical agents during the Iran-Iraq war. In April 1988, a U.N. medical specialist examined several dozen Iraqi soldiers and concluded that they could all have been exposed to mustard gas. In addition, the specialist observed symptoms in a number of patients that indicated possible exposure to “an acetylcholine esterase-inhibiting chemical in small concentrations,” which could suggest the use of a nerve agent. A 1990 DIA study also reported the allegation that Iran used sulfur mustard in some attacks, and concluded that Iran had either purchased the sulfur mustard or produced it on its own. The DIA report added 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.” Despite these findings, Iran has yet to acknowledge that it used chemical weapons during the Iran-Iraq war.

Post-War Developments and Intelligence Assessments

Although Iran claims that it terminated its chemical weapon program after the Iran-Iraq war, the United States believes that Tehran has continued-and perhaps accelerated-its drive to develop, stockpile and weaponize chemical agents after the 1988 cease-fire. In February 1997, Director of Central Intelligence George Tenet named Iran as one of about 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.”

In an assessment of Iran’s chemical weapon development released in November 2004, the CIA concluded that Iran “may have already stockpiled blister, blood, choking, and possible nerve agents-and the bombs and artillery shells to deliver them.” Earlier assessments put Iran’s stockpile of chemical agents at anywhere from several hundred to several thousand metric tons. 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.

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.” Since then, the CIA has reported that Iran was seeking “production technology, training and expertise” that could help it “achieve an indigenous capability to produce nerve agents.”

One of the most recent assessments of Iran’s chemical weapon capabilities was revealed in a February 2005 report by the German news agency ddp, citing findings by Germany’s Customs Office of Criminal Investigations (ZKA). The ZKA reportedly believes that Iran has secretly carried out chemical weapon research and development in small, well-guarded university laboratories. The ZKA further alleges that Iran probably possesses sulfur mustard, tabun, and prussic acid (hydrogen cyanide), and may possess sarin and VX.

Iran and the Chemical Weapons Convention

Iran became a State Party to the Chemical Weapons Convention (CWC) on December 3, 1997. As a member, Iran is prohibited from developing, producing or stockpiling chemical weapons. Since ratification of the CWC, Iran has maintained a high profile in the activities of the Organisation for the Prohibition of Chemical Weapons (OPCW), the international agency responsible for promoting and administering the CWC. In December 2000, José Maurício Bustani, 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.”

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. 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.”

Despite Iran’s assertions, a number of states have questioned the sincerity of Iran’s CWC compliance, as well as its motives for participating in the CWC.

A 2001 report by the U.S. State Department’s Bureau of Verification and Compliance 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. The State Department accused Iran of maintaining “an offensive R&D CW program, an undeclared stockpile and an offensive production capability.” In April 2003, U.S. Assistant Secretary of State for Arms Control Stephen Rademaker reiterated concerns that Iran “continues to seek chemicals, production technology, training, and expertise from abroad,” and he restated the U.S. government’s view that Iran “already has stockpiled blister, blood, and choking agents.”

Israel has expressed the opinion that Iran is using its membership in the OPCW as a means to mask its 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 Chemical Weapons Convention 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].”

Foreign Suppliers

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


According to the CIA, Chinese entities have been among the most active suppliers of CW-related equipment and technology. 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.

In many cases, these Chinese firms have been repeatedly singled out for punishment by the U.S. State Department. 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.” 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.” One of the Chinese individuals sanctioned in May 1997 was Q.C. Chen. 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.” Zibo Chemical Equipment Plant, one of the only firms in China capable of manufacturing large-size glass-lined chemical equipment, has been sanctioned three times since May 2002 for proliferation activities with Iran.


According to the CIA, Russian entities have also been active suppliers to Iran of CW-related equipment and technology. 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.”


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. 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 poison-gas complex. The report projected that Iran was only months away from completing the plant, which the Indian companies claimed was a pesticide factory. The CIA last identified India as one of Iran’s primary suppliers of CW-related material during the second half of 1996; India has not been singled out as a country of concern for chemical proliferation to Iran since that time.

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. 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.

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. Manbar reportedly also provided Iran with know-how and a list of equipment necessary to build factories to produce mustard gas and the nerve gases tabun, sarin and soman.