Iran has been a non-nuclear weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) since 1970, and has an advanced nuclear program that it declares to be peaceful in nature. The nuclear program has progressed significantly in the past decade, in line with Iran's 2006 announcement that it would begin enriching uranium. Tehran's failure to report significant parts of its program to the International Atomic Energy Agency (IAEA), and insistence on developing all aspects of the nuclear fuel cycle, has led many states to worry that Iran's true intention is to acquire nuclear weapons, precipitating international pressure and sanctions.

Iran is not a member of the Missile Technology Control Regime (MTCR), and is actively working to acquire, develop, and deploy a broad range of ballistic missiles and space launch capabilities. The scope and status of Iran's chemical and biological activities are unknown, but the most recent Western intelligence estimates have downgraded the likelihood that Iran maintains significant offensive chemical and biological weapons programs.

Nuclear

Mohamed Reza Shah initiated Iran's nuclear program during the 1950s with assistance from the U.S. Atoms for Peace Program. Establishing the Atomic Energy Organization of Iran (AEOI) in 1974, the Shah had ambitious plans to construct 20 nuclear power reactors, a uranium enrichment facility, and a reprocessing plant for spent fuel. [1] However, after the 1979 Iranian Revolution deposed the Shah, Ayatollah Khomeini deemed the nuclear program "un-Islamic" and ordered it terminated. In 1984, Khomeini reversed course on the issue of nuclear power and sought international partners to continue building the Bushehr reactors. [2] Currently, Iran has a robust nuclear infrastructure, including uranium mining, milling, conversion, and enrichment capabilities. [3] The most controversial dimension of the program has been Iran's effort to build up its enrichment capabilities, which could be used to produce highly enriched uranium for a nuclear weapon. This includes developing, constructing and implementing an extensive enrichment program comprising nearly 20,000 gas centrifuges at 3 major facilities. [4]

The UN Security Council has passed multiple resolutions demanding that Iran halt its enrichment activities. Negotiations to resolve the nuclear issue between Iran and the United States, Russia, France, the United Kingdom, China, and Germany (P5+1 also known as E3+3) failed during the presidency of Mahmoud Ahmadinejad, but have progressed further under President Hassan Rouhani. Several rounds of talks in Geneva in October and November 2013 culminated in a 6-month Joint Plan of Action (JPOA), and negotiations along a parallel track led to the Framework for Cooperation (FFC) between the IAEA and Iran. The JPOA obligates both Iran and the P5+1 to implement several interim steps while they work to attain “a mutually-agreed long-term comprehensive solution that would ensure Iran's nuclear programme will be exclusively peaceful.” [5] The FFC commits Iran and the IAEA to cooperate further "with respect to verification activities to be undertaken by the IAEA to resolve all present and past issues." [6]

Under the JPOA, Iran agreed to suspend enrichment activities to produce near 20% uranium hexaflouride (UF6), convert and blend down its existing stockpile of this material, halt work on the IR-40 reactor at Arak, and provide expanded IAEA access to nuclear facilities. In return, the P5+1 agreed to suspend some previous sanctions on Iran and return confiscated funds totaling as much as $7 billion. [7] The latest IAEA safeguards report released in February 2015 indicated Iran has thus far complied with the JPOA, but has yet to provide the Agency with "any explanations" as called for within the context of the FFC regarding certain past activities suspected of being related to designing a nuclear weapon. [8]

Despite some progress, Iran and the P5+1 failed to reach a comprehensive accord before the original July 20th deadline, but agreed to extend the interim agreement through November 24, 2014. [9] The extension allowed Iran access to $2.8 billion in frozen assets held abroad in exchange for converting "a portion of its 20% enriched uranium in powdered form into fuel plates for the Tehran Research Reactor, making it even less readily accessible for use in a weapons program." [10] After failing to meet this extended deadline, the negotiating parties agreed to a second, seven-month extension lasting (through June 30, 2015). Additionally, Iran and the P5+1 have set a tentative four-month deadline (through March 31, 2015) to reach a "political agreement" for a comprehensive deal, hoping to use the remaining three months to iron out the technical details and specifics of implementation. [11]

Talks between Iran and the P5+1 overran the self-imposed March 31st deadline, but the parties issued a press statement two days later outlining broad areas of agreement. The announcement noted key parameters of an eventual Joint Comprehensive Plan of Action (JCPOA): [12]

• The number of installed centrifuges in Iran will be reduced by about two-thirds, from about 19,000 to 6,104, and only 5,060 would be permitted to enrich uranium. Iran has agreed not to enrich uranium over 3.67% for 15 years.
   
• Iran will limit enrichment operations for the next 10 years to the Natanz complex using only first-generation IR-1 centrifuges, and the underground enrichment facility at Fordow will be repurposed for research and development on matters not associated with enrichment. 
   
• Iran will not enrich uranium with any of its more advanced centrifuges for at least 10 years, and will conduct "limited" researched and development.
   
• Iran's current stockpile of about 10,000 kg of low enriched uranium (LEU) will be reduced to 300 kg for 15 years.
   
• The IR-40 reactor will be redesigned and rebuilt so as not to produce weapons-grade plutonium and all spent fuel will be shipped out of the country for the reactor's lifetime. Iran will forgo plutonium reprocessing indefinitely. 
   
• In addition to enhanced monitoring and verification activities, including some apparently novel transparency measures, Iran will implement the IAEA Additional Protocol and "an agreed set of measures to address the IAEA's concerns regarding the Possible Military Dimensions (PMD) of its program."
   
• U.S. and E.U. nuclear-related sanctions will be suspended after the IAEA has verified that Iran has taken all of its key nuclear-related steps. All past UN Security Council resolutions will be lifted simultaneously with Iran's completion of nuclear-related actions addressing all key concerns. 

With the basis for a final text now in place, the parties will now begin the process of drafting a final accord and its technical annexes by June 30th.

Biological

There is very little publicly available information to determine whether Iran has bought biological weapons. Although Iran acceded to the Geneva Protocol in 1929 and ratified the Biological and Toxin Weapons Convention (BTWC) in 1973, the U.S. government in the past has accused Iran of pursuing a biological weapons program; however, more recent intelligence estimates do not suggest that such a program currently exists. A 2011 report to Congress by the Director of National Intelligence assessed that Iran "probably has the capability to produce some biological warfare (BW) agents for offensive purposes, if it made the decision to do so. […] Iran continues to expand its biotechnology infrastructure and seek dual-use technologies that could be used for BW." [13] This qualified assessment likely indicates that U.S intelligence does not have conclusive evidence of a current Iranian BW program. Historically, Iran has denied the acquisition or production of biological weapons.

Chemical

Iran suffered severe losses from Iraq's use of chemical weapons between 1982 and 1988 during the Iran-Iraq War. Consequently, Iran has significant experience with the effects of chemical warfare (CW). Iran ratified the Chemical Weapons Convention (CWC) in November 1997 and has been an active participant in the work of the Organisation for the Prohibition of Chemical Weapons (OPCW). Iran has publicly acknowledged the existence of a chemical weapons program developed during the latter stages of the 1980 to 1988 war with Iraq. After ratifying the CWC, Iran opened its facilities to international inspection and claimed that all its offensive CW activities had been terminated and the facilities destroyed prior to the treaty's entry into force.

Nevertheless, throughout the late 1990s and the early 2000s, the United States continued to claim that Iran maintained an active program for the development and production of chemical weapons. This program was alleged to include stockpiles of blood, blister, choking, and possibly nerve agents. [14] Evidence could not be found to confirm these accusations. Reflecting this uncertainty, since 2003 the U.S. intelligence community has substantially downgraded its public assessments of Iranian chemical warfare capabilities. In its unclassified report to Congress covering the year 2011, the Director of National Intelligence asserted that Iran "maintains the capability to produce chemical warfare (CW) agents and conducts research that may have offensive applications." [15] Iran denies producing or possessing chemical weapons in violation of its treaty obligations. [16]

Missile

Following the Iran-Iraq war, Iran committed itself to the development of one of the most sophisticated ballistic missile programs in the Middle East. Iran has pursued a dual track strategy, developing both liquid and solid-fueled systems. As a first step, Tehran acquired Soviet R-17/R-300 (Scud-B) and R-17M (Scud-C) missiles and production lines from North Korea (renamed Shahab-1 and Shahab-2). [17] On 22 July 1998, Iran tested a single-stage liquid-fueled Shahab-3 with a range of 1,000km. [18] Tehran declared the Shahab-3 operational in July 2003. The Shahab-3, including its guidance system and engine design, is identical to North Korea's Nodong missile. [19] With foreign assistance, Tehran produces considerable quantities of the Shahab family of missiles. [20] Seeking a longer range missile, on 11 August 2004 Iran test-fired a modified Shahab-3, the Ghadr-1, with a range of 1,600km. [21] The development of the Ghadr-1 represented the threshold and limit for modifying the existing Scud-based Shahab missiles.

Marking a significant shift in Iranian missile development and capabilities, in November 2008 Tehran successfully tested a two-stage, solid-propellant 2000 km medium-range ballistic missile (MRBM), the Sejjil. [22] Since 2008, Iran has conducted five additional tests of the Sejjil, two successfully. [23] The Sejjil has not been officially accepted into service, and technological hurdles remain before it could be used as an effective military weapon. Solid-propellant missiles offer numerous advantages over liquid-propellant missiles, and it is likely that Tehran will continue to develop the Sejjil and other solid-fueled missiles as its program moves forward. In February 2014, Iran launched a Barani missile, claimed to be capable of carrying many warheads that could be deployed against a single target. However, analysts from Jane's Defence dispute this capability on technical grounds. [24] Iran has also recently revealed an unmanned aerial vehicle (UAV) which appears to be a copy of the Lockheed Martin RQ-170 Sentinel that crashed in December 2011. [25] The specifications of the UAV, and whether it actually has stealth capabilities or is just a mock-up, are unknown at this time.

In addition to its missile program, Iran is actively developing a space launch capability. Iran successfully launched three satellites into space in February 2009, June 2011, and February 2012 aboard the Safir space launch vehicle (SLV). [26] Some analysts fear that the Safir represents the technical basis for Tehran to develop long-range ballistic missiles. [27] However, Tehran would need to significantly modify the second stage of the Safir before it could be used as an ICBM, and has not demonstrated it would be able to do so, or developed the requisite reentry vehicle for an ICBM. [28] Since 1999, the U.S. intelligence community has estimated Iran could potentially test an ICBM by 2015, but its most recent assessment from January 2014 reportedly "dials back" this estimate. [29]  Expert debate concerning Iran's technological capacity to develop ICBMs in the near future is significant and ongoing. [30]

Sources:
[1] Judith Perera, "Iran's Nuclear Industry," Middle East and North Africa, January 2006.
[2] "Iran's Nuclear Program: 1950s and 60s: Atoms for Peace," Institute for Science and International Security (ISIS), www.isisnucleariran.org.
[3] "Iran's Nuclear Fuel Cycle," Institute for Science and International Security (ISIS), www.isisnucleariran.org.
[4] David Sanger, Helen Cooper, "Iran is warned over nuclear 'deception'," The New York Times, 25 September 2009; "Implementation of the NPT Safeguards Agreement and Relevant Provisions of Security Council Resolutions in the Islamic Republic of Iran," Report by the Director General, the International Atomic Energy Agency, 7 November 2011.
[5] Joint Plan of Action, "Joint Statement between the P5+1 and Iran," Geneva, 24 November 2013, http://eeas.europa.eu.
[6] IAEA Press Release, "IAEA, Iran Sign Joint Statement on Framework for Cooperation," 11 November 2013, www.iaea.org. 
[7] Joint Plan of Action, "Joint Statement between the P5+1 and Iran," Geneva, 24 November 2013, http://eeas.europa.eu.
[8] "Implementation of the NPT Safeguards Agreement and relevant provisions of Security Council resolutions in the Islamic Republic of Iran," Report by the Director General, International Atomic Energy Agency, February 19, 2014.
[9] David E. Sanger, "Negotiators Agree to Extend Nuclear Talks Four More Months, Diplomats Say," The New York Times, July 18, 2014.
[10] Robert Einhorn, "A Justified Extension for Iran Nuclear Talks, But Hard Choices Ahead," Iran at Brookings Blog, July 19, 2014, www.brookings.edu.
[11] Laura Rozen, "Iran to limit centrifuge R&D under extension," Al-Monitor, December 1, 2014 www.al-monitor.com.
[12] "Parameters for a Joint Comprehensive Plan of Action regarding the Islamic Republic of Iran's Nuclear Program," April 2, 2015.
[13] Unclassified Report to Congress on the Acquisition of Technology Relating to Weapons of Mass Destruction and Advanced Conventional Munitions, Covering 1 January to 31 December 2011, Director of National Intelligence, www.dni.gov.
[14] Unclassified Report to Congress on the Acquisition of Technology Relating to Weapons of Mass Destruction and Advanced Conventional Munitions, 1 January through 30 June 2002, Central Intelligence Agency, www.fas.org.
[15] Unclassified Report to Congress on the Acquisition of Technology Relating to Weapons of Mass Destruction and Advanced Conventional Munitions, Covering 1 January to 31 December 2011, Director of National Intelligence, www.dni.gov.
[16] Joseph Cirincione, Jon Wolfsthal and Miriam Rajkumar, "Iran," in Deadly Arsenals: Nuclear, Biological, and Chemical Threats (Washington, DC, Carnegie Endowment for International Peace, 2005), p. 295.
[17] Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, pp. 14-17.
[18] Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, p, 22.
[19] Iran's Ballistic Missile Capabilities: A Net Assessment, London: IISS: International Institute for Strategic Studies, 2010, pp. 17-22.
[20] Theodore Postol, "A Technical Assessment of Iran's Ballistic Missile Program," Technical Addendum to the Joint Threat Assessment on Iran's Nuclear and Missile Potential, 6 May 2009,, www.ewi.info; Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, pp. 26-31.
[21] Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, p. 23.
[22] Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, pp. 54-63; Ted Postol, "Technical Addendum to the Joint Threat Assessment on Iran's Nuclear and Missile Potential – The Sejjil Ballistic Missile," EastWest Institute, 31 May 2009, www.ewi.info; "Sejil (Ashoura)," Jane's Strategic Weapon Systems, 12 February 2012, www.janes.com.
[23] Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, pp. 54-63; Ted Postol, "Technical Addendum to the Joint Threat Assessment on Iran's Nuclear and Missile Potential – The Sejjil Ballistic Missile," EastWest Institute, 31 May 2009, www.ewi.info; "Sejil (Ashoura)," Jane's Strategic Weapon Systems, 12 February 2012, www.janes.com.
[24] Jeremy Binnie, "Iran announces new missile tests," IHS Jane's Defence Weekly, 13 February 2014, www.janes.com.
[25] David Cenciotti, "Tehran has just unveiled an indigenous version of the US RQ-170 Unmanned Aerial Vehicle (UAV) captured in December 2011," The Aviationist, 11 May 2014, http://theaviationist.com. 
[26] Iran's Ballistic Missile Capabilities: A Net Assessment, Dossier, London: IISS: International Institute for Strategic Studies, 2010, pp. 26-31.
[27] Nazila Fathi and William J. Broad, "Iran Launches Satellite in a Challenge for Obama," The New York Times, 3 February 2009.
[28] Uzi Rubin, "New Developments in Iran's Missile Capabilities: Implications beyond the Middle East," Jerusalem Center for Public Affairs, August 2009, www.jcpa.org; "Iran's Nuclear and Missile Potential: A Joint Threat Assessment by U.S. and Russian Experts," The East-West Center, May 2009, http://docs.ewi.info/JTA.pdf.
[29] Jason Sherman, "Pentagon Dials Back Longstanding Assessment That Iran Could Test ICBM By 2015," Inside Defense, July 9, 2014
[30] Theodore Postol, "A Technical Assessment of Iran's Ballistic Missile Program," Technical Addendum to the Joint Threat Assessment on Iran's Nuclear and Missile Potential, 6 May 2009, www.ewi.info; Uzi Rubin, "New Developments in Iran's Missile Capabilities: Implications Beyond the Middle East," Jerusalem Center for Public Affairs, August 2009, www.jcpa.org; "Iran's Nuclear and Missile Potential: A Joint Threat Assessment by U.S. and Russian Experts," The East-West Center, May 2009, http://docs.ewi.info/JTA.pdf.