In accordance with section 1634 of the fiscal year 2021 National Defense Authorization Act (NDAA), the Deputy Assistant Secretary of Defense for Nuclear and Countering Weapons of Mass Destruction Policy asked CNA to provide an unclassified report on the nuclear programs of four countries: Russia, China, North Korea, and Iran.

In accordance with NDAA requirements, this report covers the following topics as they pertain to each country’s nuclear program: the factors that drive the country’s nuclear program, including its policies, interests, and threat perceptions; the country’s nuclear command, control, and communications; nuclear program funding and budgeting; the nuclear weapons—related activities of each country, including fissile material production and weapons and delivery system testing and exercises; nuclear weapons—related research and development (R&D); nuclear weapons R&D sites and facilities; the human capital of the scientific and technical workforce involved in nuclear programs, including matters relating to the education, knowledge, and technical capabilities of that workforce; and the country’s nuclear weapons inventory, capabilities, and deployment locations.

We have attempted to address these questions as uniformly as possible across all four countries. However, the enormous differences among them necessitated flexibility in terms of what information we presented and how we presented it. For example, Russia has a large and diverse nuclear arsenal that has been roughly on par with that of the United States for decades. In contrast, Iran does not have an active nuclear weapons program. In all cases, we have strived to ensure the following:

• The information we provide is drawn from the best, most accurate unclassified open-source research material available.
• We address each question with respect to each country as thoroughly as possible—while acknowledging that in many cases providing definitive answers may be impossible.
• We note areas of uncertainty or scholarly debate.

Some of these topics, such as arsenal sizes and weapons capabilities, are well documented in existing English-language open-source literature. Other topics, such as education and training of nuclear programs’ scientific personnel, have not been extensively researched—likely because they are inherently difficult to study. In these areas, CNA has carried out focused research using original language sources (Russian, Mandarin Chinese, Korean, and Persian-Farsi) as well as unclassified English-language resources to provide the best available insights. The paper also uses callout boxes, tables, and figures to provide additional background information and context as appropriate.

The following subsections summarize of our key findings for each country.

Russia: key findings

Because of its large arsenal of nuclear weapons, Russia poses an existential threat to the United States. Until recently, the two countries were in a relationship of mutual deterrence and numerical parity buttressed by arms control limits and intrusive monitoring and verification measures on their strategic nuclear forces that began during the Cold War. In addition to a sizeable and modernizing strategic nuclear force, Russia has a nonstrategic nuclear weapons (NSNW) arsenal that is not limited by arms control and has the capability to threaten US allies in Europe. A chief reason that Russia maintains this arsenal is to offset its perceived conventional military inferiority against the United States and NATO in the European theater.

In the ongoing Russia-Ukraine war, Russian leadership has used nuclear rhetoric to signal the possibility of nuclear escalation and to deter the United States and North Atlantic Treaty Organization (NATO) allies from direct military intervention. Russia’s strategic nuclear triad, NSNWs, and supporting nuclear complex and defense industrial base are undergoing modernization to ensure that Russia’s nuclear capabilities remain a symbol of Russia’s great power status as well as a formidable deterrent to a perceived threat of US and NATO aggression.

Nuclear weapons as ultimate guarantor of sovereignty and security

The Soviet Union officially acquired nuclear weapons in 1949 and gradually developed a triad of strategic nuclear forces consisting of strategic bombers, intercontinental ballistic missiles (ICBMs), and nuclear-powered ballistic missile submarines. Russia’s strategic nuclear forces have been steadily modernizing for more than two decades. These efforts have extended to all three legs of the Russian nuclear triad, command and control, and early warning infrastructure. Modernization has focused on preservation of a retaliatory capability and development of asymmetric capabilities that could hedge against a US breakthrough in missile defense technologies.

According to Western estimates, Russia devotes about 13.5 to 16 percent of its defense spending to its nuclear weapons program. Reports have indicated a recent increase in nuclear spending to develop new warheads and continue the procurement of relevant systems.

Moscow views nuclear weapons as the ultimate guarantor of its security and an insurance policy to protect against nuclear and large-scale conventional attacks. In Russia’s “strategic deterrence” framework, nuclear weapons also play a role in deterring global and regional threats.

Russian nuclear weapons no longer limited by arms control

Until Russia announced its suspension of the New START Treaty in February 2023, legally binding US-Russian arms control had kept Russian strategic nuclear forces around the treaty’s ceiling of 1,550 deployed strategic nuclear warheads. Open-source estimates suggest that Russia’s overall stockpile consists of 4,489 deployed and nondeployed nuclear warheads assigned to strategic and nonstrategic delivery vehicles. Of these, about 2,000 warheads are intended for NSNW, and this stockpile may expand in the future.

According to the US intelligence community, because of the damage to Russia’s ground forces and Russia’s extensive expenditure of precision-guided munitions during the Russia-Ukraine war, Russia will likely become even more reliant on nuclear weapons in the future. Nuclear use in response to nuclear or conventional aggression Russian nuclear declaratory policy focuses on the role Russia assigns to nuclear weapons and outlines conditions in which the Russian military could recommend, and the Russian political leadership could consider, employing nuclear weapons. It states:

The Russian Federation reserves the right to use nuclear weapons in response to the use of nuclear and other types of weapons of mass destruction against it and/or its allies, as well as in the event of aggression against the Russian Federation with the use of conventional weapons when the very existence of the state is in jeopardy.

But in practice, as nuclear threats by the Russian leadership in the current Russia-Ukraine war suggest, Russia’s true nuclear threshold is open to interpretation.

An extensive nuclear and missile production complex

Russia’s nuclear forces are supported by a sizable nuclear complex managed by Rosatom state-owned nuclear corporation that has been modernized and optimized since the collapse of the Soviet Union. Russia also has a vast network of defense institutes and enterprises that support the government’s procurement and employment planning of missiles and nuclear weapons–relevant systems and platforms.

Russia has extensive stocks of highly enriched uranium (HEU) and separated plutonium and is standing up additional tritium production. Today, because of its large stocks of fissile materials, Russia does not produce plutonium and may enrich only small amounts of HEU for niche uses and export to foreign clients. Recent reports suggest that Russia may be supplying HEU to China. Russia has a commercial enrichment program that supplies fuel for light water reactors for Russia’s domestic market and clients abroad as well as spent fuel reprocessing capabilities. Fissile material production enterprises include four gas centrifuge uranium enrichment facilities, one active reprocessing facility, and a new reprocessing center currently under development.
The Russian nuclear complex engages in activities to ensure that the Russian stockpile is reliable and safe. Warheads are designed, assembled, evaluated, refurbished, life extended, dismantled, and remanufactured. This work is carried out in a handful of design, production, and testing facilities.

As a successor to the Union of Soviet Socialist Republics, Russia is a signatory to numerous Cold War treaties that ban nuclear testing and is a party to the Comprehensive Nuclear-Test-Ban Treaty (CTBT). However, Russia may be engaged in activities that the US intelligence community assesses to be in contravention of its CTBT obligation of generating “zero yield” during nuclear tests. US officials allege that Russia may be conducting tests that create low nuclear yields.

Human capital is a challenge, but investment is extensive

Russia has heavily invested in the improvement of the state of its science and technology ecosystem. However, it continues to lag behind the US, China, and a handful of states in Europe and Asia with respect to R&D spending, patents, scientific publications, and university rankings. Sanctions and other restrictions on Russia after the beginning of the war in Ukraine have also affected international collaborations for Russian science, and concerns about being mobilized by the Russian armed forces have exacerbated the brain drain—the mass departure of well-educated Russians to other countries. Rosatom has taken a very active role in the development of human capital and infrastructure in nuclear-related disciplines and specialties. The state-owned corporation, which currently employs 330,000 people, estimates that it will need to hire up to 100,000 new professionals in physics, chemistry, math, information technology, and other areas by 2030 and has spearheaded numerous initiatives. Despite the challenges in Russia’s science and technology ecosystem and human capital, these issues alone are unlikely to preclude Russia from maintaining nuclear parity with the United States or holding a commanding position on the global nuclear reactor market. 

China: key findings

China is a rapidly maturing nuclear weapons state with a declared no-first-use employment policy. Historically, China maintained a relatively low number of nuclear weapons compared to the United States and Russia. People’s Republic of China (PRC) leaders viewed this “lean and effective” arsenal as a part of the PRC’s asymmetric strategic posture—maintaining low but sufficient numbers to ensure mutual vulnerability and to provide for a retaliatory strike if attacked with nuclear weapons. China’s current perceptions of an evolving global strategic landscape appear to be encouraging the modernization and expansion of its nuclear arsenal as well as extending its suite of strategic options. China is now developing a resilient nuclear triad of sea-, air-, and ground-based delivery systems (as well as testing space-based delivery systems) and may be considering changing its nuclear posture to a launch-on-warning alert level, more in alignment with the US and Russian postures.

Although China declares that it stopped producing fissile material in the 1980s, it still maintains a stockpile adequate to double its arsenal and could turn to its civilian reactors to increase its fissile stockpile. In addition, China’s research facilities; human talent in science, technology, engineering, and mathematics (STEM) fields; and state-sanctioned scientific recruitment policies and investments in STEM education likely give it the capabilities necessary to modernize and advance its nuclear arsenal in accordance with strategic demands.

China’s concept of an effective nuclear deterrent may be changing

PRC officials see advancements in technology and ballistic missile defense changing the global strategic landscape in fundamental ways that make China’s long-standing asymmetric strategic posture more vulnerable to nuclear threats and China less confident in its ability to ensure a second strike. China therefore is expanding its definition of strategic deterrence to include a larger nuclear arsenal as well as developing a range of conventional weapons, such as hypersonics and missile defense, and cyber and space capabilities that could have strategic effects.

Increasing the alert level of some of its nuclear force

PRC leaders state that China remains committed to a no-first-use policy. However, military strategists within China appear to be debating over increasing the alert level of some of China’s strategic weapons, particularly its new silo-based ICBM units. This change from historically storing nuclear warheads separate from their delivery systems to maintaining warheads mated to missiles would bring Chinese forces into closer alignment with the higher alert and readiness levels of US and Russian forces and give PRC leaders to ability to launch nuclear weapons on the warning of an incoming strike.

An expanding and diversifying nuclear arsenal to increase survivability

China has been upgrading, diversifying, and increasing its ground-based strategic ICBM arsenal and is developing new stealth air platforms and submarine-launched delivery systems to form a nascent nuclear triad. This diversification includes not only upgrades to current missile designs but also new types of ICBMs with multiple independently targetable reentry vehicle capabilities, intermediate-range ballistic missiles (IRBMs), ground-based cruise missiles, and hypersonic glide vehicles capable of carrying an ICBM into space for a fractional orbital launch. US government estimates show that China has upward of 400 operational warheads in its stockpile, and if it continues its nuclear modernization and expansion at the current pace, it will have at least 1,500 deliverable warheads by 2035. In addition, China has been constructing up to 300 ICBM silos in sites in the western and central-northern part of the country, significantly improving the People’s Liberation Army Rocket Force’s nuclear-capable missile force.

Fissile stockpile sufficient to double nuclear arsenal

Any increase in a nuclear weapons stockpile requires fissile material. China’s current stockpile of plutonium, HEU, and tritium can easily support a doubling of the stockpile, but to triple or quadruple the numbers of nuclear weapons in its arsenal would likely require production of additional material. Given that China likely ended its military production of plutonium in the 1980s, nuclear experts assess that it could theoretically turn to its civil reactors for additional plutonium. This additional production could occur under the PRC’s “military-civil fusion” plan, a national strategy aimed at eliminating barriers between China's civilian research and commercial sectors and its military and defense industrial sectors.

Scientific personnel likely adequate to meet its strategic development goals

China is investing heavily in its STEM education system, has a national mandate to become self-reliant in its technology sector, and has more than 200 state-sanctioned talent recruitment programs incentivizing high-level PRC-born scientists to return to China. In addition, China has a high concentration of universities offering degree programs directly linked to the nuclear technology field; 72 universities in China run programs on nuclear engineering, 47 of which have separate schools on nuclear science, compared with 34 institutions in the United States that offer nuclear engineering programs. Although China’s top STEM universities are not the
most elite ranked schools globally, they still are rated in the top 10 percent on average for global school rankings. These factors indicate that the PRC likely has a relatively large, high-quality scientific talent pool that is capable of modernizing and advancing the PRC’s  nuclear weapons program to meet its strategic objectives. 

North Korea: key findings

North Korea is committed to becoming a regional nuclear power with the ability to strategically deter the United States. Pyongyang’s desire for a nuclear weapons program dates to the earliest years of the state and is intrinsically linked to ensuring the security of the Kim family regime. Under Kim Jong Un, North Korea has consistently and steadily made progress toward this goal despite unprecedented international efforts to dissuade the regime in the form of diplomatic pressure and international sanctions. As of 2023, North Korea has conducted six nuclear tests and hundreds of tests of short-, medium-, and long-range missile systems. Although questions remain about the status of North Korea’s ICBM capability, Pyongyang has demonstrated many capabilities that can be used to target vital US interests in Northeast Asia and the Pacific and has signaled that the development of its nuclear deterrent will be an enduring priority for the regime. North Korea’s continued development of an ICBM could position Pyongyang to directly threaten the United States homeland as part of a strategy to deter outside aggression against the regime.

Guarantor of regime survival

The drivers of North Korea’s nuclear program include both historical and ideological factors. Strategic decision-making by North Korea’s rulers has primarily been driven by two key objectives: regime survival and perpetuation of the Kim family’s rule. North Korea, as an economically and diplomatically isolated state, views nuclear weapons as the ultimate guarantor of its security and a deterrent to any attempt at regime change. This perception hardened amid North Korea’s growing military and economic weakness vis-à-vis US-allied South Korea. In the post–Cold War time frame, North Korea’s interpretation of the international security environment contributed to the calculus that without nuclear weapons it would be vulnerable to potential US-led efforts to overthrow the Kim regime.

The ideological foundation of the North Korean regime rests on the philosophy of Juche, which means “agency” but is often translated as “self-reliance.” The nuclear program and national ideology are inextricably linked in that they feed off each other with respect to how the regime portrays itself to the people and how the people view the legitimacy of the regime. Possibly more important to the Supreme Leader and the wider leadership, the nuclear program undergirds the ideology by providing the means by which Juche can be executed. By providing the “treasured sword” to protect the North Korean people, the nuclear program conveys legitimacy on the regime as the provider of that sword as well as on the Supreme Leader.

Toward a strategic capability

As a nascent nuclear state, North Korea’s nuclear activities are focused on R&D in pursuit of a nuclear weapons capability that can credibly threaten the United States and its allies. These activities include the full range of steps that a state must take to advance its military nuclear program, including fissile material production and warhead and missile testing. North Korea has built out its national infrastructure and organizational structure to support the activities of its nuclear and ballistic missile enterprises, including the development of a robust domestic science and technology capability that allows the regime to rely on indigenous personnel and expertise as it advances its program. North Korea is developing a diverse inventory of strategic and tactical ballistic missiles and multiple delivery systems. These include ICBMs as well as IRBMs, medium-range ballistic missiles, short-range ballistic missiles, and sea-launched ballistic missiles. North Korea has pursued both ground- and sea-launched missile systems and prioritized mobile-based systems in what appears to be an attempt to make its launch systems more survivable. It is unclear how many missiles North Korea has in its arsenal; however, in his public statements, Kim Jong Un has emphasized the need to mass produce the elements of North Korea’s strategic arsenal, including warheads and ballistic missiles. During the Kim Jong Un period, North Korea has expanded the number of testing sites for its missile program across the country, indicating a potential desire to be able to disperse and launch its ballistic missiles from more locations.

Based on North Korea’s estimated ability to produce fissile material, outside analysts have posited that North Korea may have between 40 and 60 nuclear weapons, but some analysts have estimated that North Korea could have as many as 100 warheads in its current inventory. There is speculation regarding the characteristics of North Korea’s nuclear weapons, but experts have generally concluded that North Korea likely has implosion devices and possibly a thermonuclear device. North Korea’s six nuclear tests (2006, 2009, 2013, 2016 (2), 2017) have demonstrated increasingly higher detonation yields. North Korea has claimed progress toward miniaturizing warheads to fit on its missiles. However, several questions remain regarding North Korea’s ability to operationalize its nuclear warhead inventory. North Korea has yet to demonstrate or prove that it can successfully mate a warhead with a ballistic missile, although some experts posit that North Korea likely has a capability to put a warhead on its short- and medium-range missiles.

Emerging nuclear doctrine

As North Korea’s nuclear program has developed, Pyongyang has incrementally clarified its emergent nuclear policy through public statements, legislative activities, and political rhetoric. During the Kim Jong Un era, North Korea has consistently emphasized the defensive nature of its nuclear weapons program while simultaneously alluding to its potential for preemptive and offensive employment if it were to be threatened or attacked. In recent years, a shift in North Korea’s rhetoric has more explicitly emphasized the possible preemptive use of nuclear weapons and potential employment of tactical nuclear weapons and provided more insight on conditions that would affect North Korean nuclear decision-making.

In 2022, North Korea’s Supreme People’s Assembly passed DPRK’s Law on Policy of Nuclear Forces, which provides the most clarity on North Korea’s nuclear employment policy and nuclear command and control. The law states that the primary missions of the country’s nuclear forces are to deter attack and counter or repel an attack should deterrence fail. The law also describes various conditions in which North Korea would employ nuclear weapons. The law reiterates North Korea’s position that nuclear weapons would be used only in a scenario in which the regime was threatened.

Enduring priority for the Kim regime

North Korea has consistently emphasized the central role of the country’s nuclear capability for its security. Kim Jong Un is frequently depicted attending events related to the country’s nuclear and missile programs and has begun including his young daughter, signaling North Korea’s enduring commitment to its nuclear deterrent and prioritization of national resources toward these programs. Sanctions and international pressure have curtailed North Korea’s nuclear progress and access to foreign support and material, but North Korea has demonstrated that it can continue to fund these programs, develop new capabilities, and demonstrate technological progress despite these barriers. North Korea has proven adept at adapting to sanctions and using licit and illicit means to fund its nuclear and missile activities, which outside analysts estimate to cost between $500 million and $1 billion annually. North Korea’s evolving nuclear doctrine of preemptive use to deter aggression based on its perception of imminent threat highlights North Korea’s pursuit of an operationalized strategic and tactical nuclear capability.

Iran: key findings

Iran does not currently possess nuclear weapons nor does it appear to have an active nuclear weapons program. However, Iran has engaged in activities relevant to developing nuclear weapons should Iran’s leadership decide to pursue such an initiative. These activities include producing HEU and conducting research and experiments with warhead design, metallurgy, and mating warheads with missiles. Iran also has the largest ballistic missile inventory in the Middle East. Although these systems are conventionally armed, they could potentially be adapted to deliver nuclear payloads. In addition, Iran has an active space launch vehicle program that could serve as the basis for ICBM development should Tehran desire to acquire such a system.

In July 2015, negotiations between Iran and the P5+1 resulted in the Joint Comprehensive Plan of Action (JCPOA), a 25-year agreement limiting Iran’s nuclear capacity and subjecting the country to stringent inspections in exchange for sanctions relief. However, doubts about the Iranian government’s transparency regarding its nuclear program lingered. In May 2018, the US unilaterally withdrew from the JCPOA, reimposing nuclear-related sanctions on Iran. In response, Iran resumed enriching uranium beyond JCPOA-mandated limits.

Nuclear weapons program shelved in 2003

Iran’s efforts to develop a nuclear explosive device began in the late 1980s under the auspices of the Iranian Ministry of Defense and Armed Forces Logistics. The military’s efforts were later consolidated within the AMAD Project, which produced components and mock-up parts for engineering a reentry vehicle for a nuclear warhead, conducted engineering studies that examined how to integrate a new spherical payload into the existing payload chamber of a ballistic missile reentry vehicle, and conducted computer modeling studies to evaluate prototypes of missile reentry vehicles, including a prototype firing system for a missile payload that would allow the warhead to safely reenter the atmosphere and then explode above a target or upon impact. According to the International Atomic Energy Agency (IAEA), which has conducted two investigations into Iran’s past nuclear activities, a “range of activities relevant to the development of a nuclear explosive device were conducted in Iran prior to the end of 2003 as a coordinated effort, and some activities took place after 2003.”  The IAEA’s investigations into the military dimensions of Iran’s nuclear program have found “no credible indications” of activities relevant to weaponization after 2009 or any diversion of nuclear materials for military purposes. 

Enrichment a source of concern

Current concerns about Iran’s nuclear program are mostly focused on the country’s enrichment activities, especially Iran’s use of advanced gas centrifuges to generate HEU from hexafluoride (UF6) gas. HEU is one of the two types of fissile material (the other is plutonium) that can be used in nuclear weapons. According to the IAEA, the Atomic Energy Agency of Iran appears to have mastered all the stages of nuclear reactor fuel production. Furthermore, Iran has developed the necessary infrastructure to support each phase of the enrichment process. Iran has three enrichment facilities: an aboveground Pilot Fuel Enrichment Plant at Natanz, an underground Fuel Enrichment Plant also at Natanz, and the deeply buried Fordow Fuel Enrichment Plant.  Iran also operates a yellowcake  production plant at Ardakan, a UF6 conversion facility in Esfahan, a uranium mine at Gchine, and a uranium production plant for processing uranium ore near Bandar Abbas.

The JCPOA capped Iran’s enrichment at 3.57 percent HEU, suitable for powering a civilian nuclear reactor but far short of the 90  percent required for a nuclear weapon. However, following the US withdrawal from the JCPOA, Iran began to install more advanced centrifuges at its enrichment facilities and to incrementally increase the levels at which it was enriching uranium. On February 28, 2023, the IAEA assessed that Iran had produced 87.5 kilograms (192.9 pounds) of uranium enriched to 60 percent using advanced IR-6 centrifuges.  Uranium enriched to this level has no practical civilian purpose, but it could vastly reduce the time required for Iran to achieve a nuclear breakout capability. On March 29, 2023, General Mark Milley, the chairman of the US Joint Chiefs of Staff, warned that the time Iran needed to produce enough HEU at a suitable level for one bomb was down to 10 to 15 days.

Large inventory of potential delivery systems

Iran has the largest ballistic missile inventory in the Middle East, including more than 1,000 close-, short-, medium-, and intermediate-range missiles and a smaller inventory of land-attack cruise missiles. Before 2003, the Iranian military had conducted research on weapons design and mating nuclear warheads with ballistic missiles.  United Nations Security Council Resolution (UNSCR) 2231, which endorses the JCPOA, calls upon Iran not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology.  The Iranian government has asserted that conventionally armed ballistic missiles are essential to the country’s defense and are not designed for nuclear use and are thus outside the purview of UNSCR 2231 and its annexes. Successive US administrations have considered Iran’s development, acquisition, and use of ballistic missiles as “provocative and destabilizing” and “inconsistent with” UNSCR 2231 because of their inherent capability to carry a nuclear warhead. Iran is not a signatory to international regimes to prevent missile proliferation, such as the Missile Technology Control Regime.

Brain drain limits nuclear talent

Iran’s nuclear program has benefited from Iranian students returning from abroad with advanced degrees in STEM-related subjects, particularly physics and nuclear engineering. In 2020 to 2021, approximately 130,000 Iranian-born students were enrolled in foreign
universities, including 9,614 in US universities, making Iran the 13th highest ranking country as a source of foreign students studying in the US. However, Iran is also experiencing a “brain drain,” which has significantly reduced the pool of available academic talent in Iran. Enticed by the prospect of better, higher paying jobs and financial and political stability, many Iranian students traveling abroad for their education now tend to stay abroad after they earn their degrees. Unlike China, which has invested heavily in strategies to retain academic talent, Iran has tended to downplay or ignore the issue of academic flight, suggesting that the problem is likely to persist, especially if the country continues to experience high levels of unemployment and political unrest.