Pentagon’s report to Congress says China’s nuclear stockpile includes over 500 warheads

The Pentagon’s 2023 report to US Congress assessed that China’s nuclear stockpile now includes over 500 warheads.

The modernization of China’s nuclear arsenal has both accelerated and expanded in recent years. Within the past five years, China has significantly expanded its ongoing nuclear modernization program by fielding more types and greater numbers of nuclear weapons than ever before. Since our previous edition on China in March 2023, China has continued to develop its three new missile silo fields for solid-fuel intercontinental ballistic missiles (ICBMs), expanded the construction of new silos for its liquid-fuel DF-5 ICBMs, has been developing new variants of ICBMs and advanced strategic delivery systems, and has likely produced excess warheads for eventual upload onto these systems once they are deployed. China has also further expanded its dual-capable DF-26 intermediate-range ballistic missile force, which appears to have completely replaced the medium-range DF-21 in the nuclear role. At sea, China has been refitting its Type 094 ballistic missile submarines with the longer-range JL-3 submarine-launched ballistic missile. In addition, China has recently reassigned an operational nuclear mission to its bombers and is developing an air-launched ballistic missile that might have nuclear capability. In all, China’s nuclear expansion is among the largest and most rapid modernization campaigns of the nine nuclear-armed states, Bulletin of the Atomic Scientists reports.

We estimate that China has produced a stockpile of approximately 440 nuclear warheads for delivery by land-based ballistic missiles, sea-based ballistic missiles, and bombers. Roughly 60 more warheads have thought to have been produced, with more in production, to eventually arm additional road-mobile and silo-based missiles and bombers.

The Pentagon’s 2023 report to Congress assessed that China’s nuclear stockpile now includes over 500 warheads, in accordance with our own estimate. The Pentagon also estimates that China’s arsenal will increase to about 1,000 warheads by 2030, many of which will probably be “deployed at higher readiness levels” and most “fielded on systems capable of ranging the [continental United States]. If expansion continues at the current rate, the Pentagon’s previous projections say that China might field a stockpile of about 1,500 nuclear warheads by 2035.

These projections depend on many uncertain factors, including:

How many missile silos China will ultimately build;

How many silos China will load with missiles;

How many warheads each missile will carry;

How many DF-26 intermediate-range ballistic missiles will be deployed and how many of them will have a nuclear mission;

How many missile submarines China will field and how many warheads each missile will carry;

How many bombers China will operate and how many weapons each will carry; and

Assumptions about the future production of fissile materials by China.

Several US government estimates about China’s nuclear weapons stockpile growth have previously proven inaccurate. The latest Pentagon projection appears to simply apply the same growth rate of new warheads added to the stockpile between 2019 and 2021 to the subsequent years until 2035. We assess that this projected growth trajectory is feasible but depends significantly upon answers to the above questions.

Fissile materials production

How much and how fast China’s stockpile can grow will depend upon its inventories of plutonium, highly enriched uranium (HEU), and tritium. The International Panel on Fissile Materials assessed that at the end of 2022, China had a stockpile of approximately 14 tonnes (metric tons) of HEU and approximately 2.9 tonnes of separated plutonium in or available for nuclear weapons (Kütt, Mian, and Podvig 2023, 328–329). The existing inventories were sufficient to support a doubling of the stockpile over the past five years. However, producing more than 1,000 additional warheads by 2035, as estimated by the Pentagon, would require additional fissile material production. The Pentagon assesses that China is expanding and diversifying its capability to produce tritium (US Department of Defense 2023, 110). In 2023, China also reportedly began operating two large new centrifuge enrichment plants, and also took a significant step forward with its domestic plutonium production capabilities (Zhang 2023a, 2023b).

Chinese production of weapon-grade plutonium reportedly ceased in the mid-1980s (Zhang 2018). However, Beijing is combining its civilian technology and industrial sector with its defense industrial base to leverage dual-use infrastructure (US Department of Defense 2023, 28). It is believed that China likely intends to acquire significant stocks of plutonium by using its civilian reactors, including two commercial-sized CFR-600 sodium-cooled fast-breeder reactors that are currently under construction at Xiapu in Fujian province (Jones 2021; von Hippel 2021; Zhang 2021b). Rosatom—Russia’s state-controlled nuclear energy company—completed the final delivery of fuel to supply the first fuel loading in December 2022 (Rosatom 2022), and steam possibly seen emanating from a cooling tower on satellite imagery in October 2023 suggests the first CFR-600 reactor may have begun operation (Kobayashi 2023). In December 2023, the International Panel on Fissile Materials reported that the first reactor reportedly began operating at low-power mode in mid-2023, although as of October 2023 it had not yet been connected to the grid and had not yet begun generating electricity (Zhang 2023a). The second reactor is scheduled to come online by 2026.

To extract plutonium from its spent nuclear fuel, China has nearly completed its first civilian “demonstration” reprocessing plant at the China National Nuclear Corporation (CNNC) Gansu Nuclear Technology Industrial Park in Jinta, Gansu province, which is expected to be operational in 2025. China has started the construction of a second plant at the same location, which should be up and running before the end of the decade (Zhang 2021a). The 200 tonne-per-year fuel reprocessing capacity at Jinta and the 50 tonne-per-year capacity at Jiuquan (Plant 404) could support the plutonium needs of the two CFR-600 reactors, especially since the first of these reactors will begin operation with highly enriched uranium (HEU) rather than mixed oxide (MOX) fuel through a supply agreement with Russia (US Department of Defense 2023, 109; Zhang 2021a).

The ambiguity of Chinese nuclear warhead types and uncertainty on the exact amount of fissile material required for each warhead design make it difficult to estimate how many weapons China could produce from its existing HEU and weapons-grade plutonium stockpiles. Once both fast-breeder reactors come online, they could potentially produce large amounts of plutonium and, by some estimates, could enable China to acquire over 330 kilograms of weapon-grade plutonium annually for new warhead production (Kobayashi 2023)—which would be consistent with the Pentagon’s most recent projections.

While China’s production and reprocessing of fissile materials is consistent with its nuclear power efforts and its goal of reaching a closed nuclear fuel cycle, the Pentagon suggests that “it is likely that Beijing intends to use this infrastructure to produce nuclear warhead materials for its military in the near term” (US Department of Defense 2023, 109). The degree of transparency surrounding China’s nuclear materials production and its suspected expansion of uranium and tritium production has recently decreased as China has not reported its separated plutonium stockpile to the International Atomic Energy Agency since 2017.

US estimates and assumptions about Chinese nuclear forces

Evaluation of current US projections about the future size of China’s nuclear weapons stockpile must take earlier projections into account, some of which did not come to pass. During the 1980s and 1990s, US government agencies published several projections for the number of Chinese nuclear warheads. A US Defense Intelligence Agency study from 1984 inaccurately estimated that China had 150 to 360 nuclear warheads and projected it could increase to more than 800 by 1994 (Kristensen 2006). Over a decade later, another Defense Intelligence Agency study published in 1999 projected that China might have over 460 nuclear weapons by 2020 (US Defense Intelligence Agency 1999). While this latter projection ultimately proved to be closer to the warhead estimate the Pentagon published in 2020, it was still more than twice the “low-200s” warhead estimate announced by the Pentagon.

Current US projections should be read with this record in mind. In November 2021, the Pentagon’s annual China Military Power Report (CMPR) to Congress projected that China could have 700 deliverable warheads by 2027, and possibly as many as 1,000 by 2030 (US Department of Defense 2021, 90). The 2022 Pentagon report increased the projection even further, claiming that China’s stockpile of “operational” nuclear warheads had surpassed 400 and will likely reach about 1,500 warheads by 2035 (US Department of Defense 2022b, 94). According to the latest 2023 CMPR, China “had more than 500 operational nuclear warheads” as of May 2023 and is on track to have over 1,000 operational warheads by 2030 as previously reported (US Department of Defense 2023, viii). The observable operational force structure, however, does not add up to more than 500 operational warheads (this report estimates approximately 440) unless the Pentagon estimate attributes nuclear warheads to all the DF-26 launchers (which seems excessive), several dozen new missile silos have been loaded with missiles (which is possible, but we have not yet seen indications of widespread loading operations with commercial satellite imagery), or the estimate includes new warheads in production for new missiles. To that effect, this report estimates that China’s stockpile numbers approximately 500 warheads; however, we assess that several dozen of these have not yet been fielded and have likely been produced (or are in production) to eventually arm incoming delivery systems. Curiously, the 2023 report does not repeat the 1,500-warhead projection for 2035.

After the release of the 2022 CMPR, the spokesperson for China’s Ministry of National Defense, Senior Col. Tan Kefei, reacted saying that the Pentagon was “distorting China’s national defense policy and military strategy, groundlessly speculating about China’s military development” (Li 2022a). The following year, spokesperson Wu Qian criticized the 2023 CMPR, saying it “exaggerated and sensationalized the non-existent ‘Chinese military threat’” (Ministry of National Defense of the People’s Republic of China 2023a). None of the two spokespersons acknowledged—nor denied—the expansion of the mobile ICBM force or the construction of three large new missile silo fields.

The projected increase has unsurprisingly triggered a wide range of speculations about China’s nuclear intentions. In 2020, Trump administration officials suggested that “China no longer intends to field a minimal deterrent,” and instead strives for “a form of nuclear parity with the United States and Russia” (Billingslea 2020). These statements were echoed in August 2021 by the Deputy Commander of US Strategic Command, who stated that: “There’s going to be a point, a crossover point, where the number of threats presented by China will exceed the number of threats that currently Russia presents,” noting that this point would likely be reached “in the next few years” (Bussiere 2021). In April 2022, the commander of the US Strategic Command, Adm. Charles Richard, referred to China’s expansion of its strategic and nuclear forces as “breathtaking,” later stating that China was intent on pursuing a “world-class military by 2030, and the military capabilities to seize Taiwan by force, if they choose to, by 2027” (US Strategic Command 2022). He also referred to China’s “investments in nuclear command and control” and “nascent launch under warning, launch under attack” capabilities as clear signs that they have improved their readiness and “moved a long way off the historic minimum-deterrence posture” (US Strategic Command 2022). In March 2023, the Commander of the US Strategic Command (STRATCOM), Gen. Anthony Cotton, conveyed a similar perspective, testifying that “China seeks to match, or in some areas surpass, quantitative and qualitative parity with the United States in terms of nuclear weapons. China’s nuclear capabilities already exceed those needed for its long-professed policy of ‘minimum deterrence,’ but China’s capabilities continue to grow at an alarming rate” (Cotton 2023).

Even the worst-case projection of 1,500 warheads by 2035 amounts to less than half of the current US nuclear stockpile, so the Chinese government uses the disparity in total warhead numbers to argue it is “unrealistic to expect China to join [the United States and Russia] in a negotiation aimed at nuclear arms reduction” (Ministry of National Defense of the People’s Republic of China 2020). While highlighting the increase of Chinese warheads, US defense officials at the same time downplay the importance of numbers when reminded that the United States has many more: “We don’t approach it from purely a numbers game,” according to the deputy commander of the US Strategic Command, Lt. Gen. Thomas Bussiere. “It is what is operationally fielded, … status of forces, posture of those fielded forces. So, it is not just a stockpile number,” he said (Bussiere 2021).

Nuclear testing

The projection for how much the Chinese nuclear stockpile will increase also depends on the size and design of its warheads. China’s nuclear testing program of the 1990s partially supported development of the warhead type currently arming the DF-31-class ICBMs. This warhead may also have been used to equip the liquid-fueled DF-5B ICBM with multiple independently targeted reentry vehicle (MIRV) technology, replacing the much larger warhead used on the DF-5A. The large DF-41 and the JL-3 could potentially use the same smaller warhead. The Pentagon believes that China probably seeks a “lower-yield” nuclear warhead for the DF-26 (US Department of Defense 2023, 111), however it is unclear if that implies production of a new warhead or how low a “lower” yield is; the warhead for the DF-31 and DF-41 are also thought to have lower yield than the warhead deployed on the DF-5A.

Open-source satellite imagery analysis indicates that China appears to be expanding the Lop Nur test site with the construction of approximately a dozen concrete buildings near the site’s airfield, as well as at least one new tunnel at the site’s northern testing area (Brumfiel 2021b). Satellite imagery shows what appears to be new drainage areas, drill rigs, roads, spoil piles, and covered entrances to potential underground facilities, as well as new construction at the main administration, support, and storage areas. Many of these activities remained visible as of the time of writing this report. In addition to new activity at the northern tunnel test area, satellite imagery also indicated activity at a possible new eastern test area at Lop Nur (Babiarz 2023). Although the construction works are significant, they do not necessarily prove that China plans to conduct new nuclear detonations at the test site. If China did conduct low-yield nuclear tests at Lop Nur, it would violate its responsibility under the Comprehensive Test Ban Treaty it has signed but not ratified.