Pakistan's nuclear arsenal probably consists of approximately 90-110 nuclear warheads, although it could be larger. Islamabad is producing fissile material, adding to related production facilities, and deploying additional delivery vehicles. These steps could enable Pakistan to undertake both quantitative and qualitative improvements to its nuclear arsenal. Whether and to what extent Pakistan's current expansion of its nuclear weapons-related facilities is a response to the 2008 U.S.-India nuclear cooperation agreement is unclear. Islamabad does not have a public, detailed nuclear doctrine, but its "minimum credible deterrent" is widely regarded as designed to dissuade India from taking military action against Pakistan.

India, which has not signed the Nuclear Nonproliferation Treaty and does not have International Atomic Energy Agency safeguards on all of its nuclear material, exploded a "peaceful" nuclear device in 1974, convincing the world of the need for greater restrictions on nuclear trade. The United States created the Nuclear Suppliers Group (NSG) as a direct response to India's test, halted nuclear exports to India a few years later, and worked to convince other states to do the same. India tested nuclear weapons again in 1998. However, President Bush announced July 18, 2005, he would "work to achieve full civil nuclear energy cooperation with India" and would "also seek agreement from Congress to adjust U.S. laws and policies," in the context of a broader partnership with India. U.S. nuclear cooperation with other countries is governed by the Atomic Energy Act (AEA) of 1954 (P.L. 95-242). However, P.L. 109-401, which President Bush signed into law on December 18, 2006, allows the President to waive several provisions of the AEA. On September 10, 2008, President Bush submitted to Congress, in addition to other required documents, a written determination that P.L. 109-401's requirements for U.S. nuclear cooperation with India to proceed had been met. President Bush signed P.L. 110-369, which approved the agreement, into law October 8, 2008. Then-Secretary of State Condoleezza Rice and India's then-External Affairs Minister Shri Pranab Mukherjee signed the agreement two days later, and it entered into force December 6, 2008. Additionally, the United States and India signed a subsequent arrangement in July 2010 which governs "arrangements and procedures under which" India may reprocess U.S.-origin nuclear fuel in two new national reprocessing facilities, which New Delhi has not yet constructed. The NSG, at the behest of the Bush Administration, agreed in September 2008 to exempt India from some of its export guidelines. That decision has effectively left decisions regarding nuclear commerce with India almost entirely up to individual governments. Since the NSG decision, India has concluded numerous nuclear cooperation agreements with foreign suppliers. However, U.S. companies have not yet started nuclear trade with India and may be reluctant to do so if New Delhi does not resolve concerns regarding its policies on liability for nuclear reactor operators and suppliers. Taking a step to resolve such concerns, India signed the Convention on Supplementary Compensation for Nuclear Damage, which has not yet entered into force, October 27, 2010. However, many observers have argued that Indian nuclear liability legislation adopted in August 2010 is inconsistent with the Convention. The Obama Administration has continued with the Bush Administration's policy regarding civil nuclear cooperation with India. According to a November 8, 2010, White House fact sheet, the United States "intends to support India's full membership" in the NSG, as well as other multilateral export control regimes.

Arms control and nonproliferation efforts are two of the tools that have occasionally been used to implement U.S. national security strategy. Although some believe these tools do little to restrain the behavior of U.S. adversaries, while doing too much to restrain U.S. military forces and operations, many other analysts see them as an effective means to promote transparency, ease military planning, limit forces, and protect against uncertainty and surprise. Arms control and nonproliferation efforts have produced formal treaties and agreements, informal arrangements, and cooperative threat reduction and monitoring mechanisms. The pace of implementation for many of these agreements slowed during the Clinton Administration, and the Bush Administration usually preferred unilateral or ad hoc measures to formal treaties and agreements to address U.S. security concerns. But the Obama Administration resumed bilateral negotiations with Russia and pledged its support for a number of multilateral arms control and nonproliferation efforts.

In 2002, the International Atomic Energy Agency (IAEA) began investigating allegations that Iran had conducted clandestine nuclear activities. Ultimately, the agency reported that some of these activities had violated Tehran's IAEA safeguards agreement. The IAEA has not stated definitively that Iran has pursued nuclear weapons, but has also not yet been able to conclude that the country's nuclear program is exclusively for peaceful purposes. The IAEA Board of Governors referred the matter to the U.N. Security Council in February 2006. Since then, the council has adopted six resolutions, the most recent of which (Resolution 1929) was adopted in June 2010. The Security Council has required Iran to cooperate fully with the IAEA's investigation of its nuclear activities, suspend its uranium enrichment program, suspend its construction of a heavywater reactor and related projects, and ratify the Additional Protocol to its IAEA safeguards agreement. However, a November 2011 report from IAEA Director-General Yukiya Amano to the agency's Board of Governors indicated that Tehran has continued to defy the council's demands by continuing work on its uranium enrichment program and heavy-water reactor program. Iran has signed, but not ratified, its Additional Protocol. Iran and the IAEA agreed in August 2007 on a work plan to clarify the outstanding questions regarding Tehran's nuclear program. Most of these questions have essentially been resolved, but then-IAEA Director-General Mohamed ElBaradei told the agency's board in June 2008 that the agency still has questions regarding "possible military dimensions to Iran's nuclear programme." The IAEA has reported for some time that it has not been able to make progress on these matters. This report provides a brief overview of Iran's nuclear program and describes the legal basis for the actions taken by the IAEA board and the Security Council.

Iran's nuclear program began during the 1950s. The United States has expressed concern since the mid-1970s that Tehran might develop nuclear weapons. Iran's construction of gas centrifuge-based uranium enrichment facilities is currently the main source of proliferation concern. Gas centrifuges enrich uranium by spinning uranium hexafluoride gas at high speeds to increase the concentration of the uranium-235 isotope. Such centrifuges can produce both low-enriched uranium (LEU), which can be used in nuclear power reactors, and weapons-grade highly enriched uranium (HEU), which is one of the two types of fissile material used in nuclear weapons.

The United States has long recognized the dangers inherent in the spread of nuclear, biological, and chemical (NBC) weapons, and missiles. This report, which analyzes NBC weapons programs potential threat patterns around the globe, is updated as needed.

This report is prepared annually to provide Congress with official, unclassified, quantitative data on conventional arms transfers to developing nations by the United States and foreign countries for the preceding eight calendar years for use in its policy oversight functions. All agreement and delivery data in this report for the United States are government-to-government Foreign Military Sales (FMS) transactions. Similar data are provided on worldwide conventional arms transfers by all suppliers, but the principal focus is the level of arms transfers by major weapons suppliers to nations in the developing world.

Pakistan's nuclear arsenal probably consists of approximately 90-110 nuclear warheads, although it could be larger. Islamabad is producing fissile material, adding to related production facilities, and deploying additional delivery vehicles. These steps could enable Pakistan to undertake both quantitative and qualitative improvements to its nuclear arsenal. Whether and to what extent Pakistan's current expansion of its nuclear weapons-related facilities is a response to the 2008 U.S.-India nuclear cooperation agreement is unclear. Islamabad does not have a public, detailed nuclear doctrine, but its "minimum credible deterrent" is widely regarded as designed to dissuade India from taking military action against Pakistan. Pakistan has in recent years taken a number of steps to increase international confidence in the security of its nuclear arsenal. In addition to overhauling nuclear command and control structures since September 11, 2001, Islamabad has implemented new personnel security programs. Moreover, Pakistani and some U.S. officials argue that, since the 2004 revelations about a procurement network run by former Pakistani nuclear official A. Q. Khan, Islamabad has taken a number of steps to improve its nuclear security and to prevent further proliferation of nuclearrelated technologies and materials. A number of important initiatives, such as strengthened export control laws, improved personnel security, and international nuclear security cooperation programs have improved Pakistan's security situation in recent years. However, instability in Pakistan has called the extent and durability of these reforms into question. Some observers fear radical takeover of a government that possesses a nuclear bomb, or proliferation by radical sympathizers within Pakistan's nuclear complex in case of a breakdown of controls. While U.S. and Pakistani officials continue to express confidence in controls over Pakistan's nuclear weapons, continued instability in the country could impact these safeguards.