Strategic Command Sounds Questionable Alarm on Chinese Nuclear Buildup

April 13, 2022 | 2:56 pm
Alejandro Luengo/Unsplash
Gregory Kulacki
China Project Manager

Admiral Charles Richard, the commander of the United States Strategic Command (STRATCOM), recently told House appropriators China accomplished a “strategic breakout” that “requires the DoD to make immediate and significant planning and/or capability shifts.” Before Congress decides to spend hundreds of billions of dollars to pay for those shifts, members should look more carefully at the facts. STRATCOM may be overreacting.

Richard defined this supposed breakout as “a rapid qualitative and quantitative expansion of military capabilities” and said the expansion of China’s nuclear forces was “breathtaking.” China is increasing the size of its nuclear arsenal, but the pace and scale of change is unlikely to be as alarming as Richard suggests.

China’s plutonium problem

The most important constraint on the expansion of China’s nuclear force is the amount of weapons grade plutonium China has available to manufacture nuclear warheads. China produced a very limited amount of weapons-grade plutonium before halting production and shutting down its facilities towards the end of the Cold War. The most credible open-source estimate of the amount of plutonium available for warheads is approximately 3.5 tonnes. The United States has 87.7 tonnes.

A reliable open source estimate of the amount of plutonium used in China’s smallest tested warhead suggests it contains between 4 and 6 kilograms. If we split the difference, China made enough plutonium to manufacture approximately 700 of them. Richard claims China will double its current 350 to reach that number by 2027. He claims they will have 1,000 by 2030. That’s possible given the potential for variation in the estimates. But it is equally possible China does not have enough weapons-grade plutonium to reach those numbers. In either case, China cannot expand its nuclear arsenal much beyond this self-imposed cap without producing more plutonium.

Richard seems to be aware of that limitation. He claimed it was “highly likely” China will attempt to solve its plutonium problem by diverting some of the metal from its civilian nuclear program. The two options he mentioned were plutonium extracted from the spent fuel of civilian power reactors and the plutonium that will be produced in China’s two experimental fast breeder reactors. Both options are possible, but neither is ideal.

Using the civilian power reactor program to obtain weapons-grade plutonium would require more frequent and shorter fuel cycles, disrupting electricity production amid chronic shortages. It would also require some adjustments to the process normally used to reprocess spent power reactor fuel. Finally, using plutonium extracted in this way might require adjustments to China’s tested weapons designs. 

China’s two experimental fast breeders will produce electricity and weapons-grade plutonium at the same time. But not a lot of it. If all goes well, each reactor will produce about 170kg of the metal each year. At that rate, it would take several hundred years for China to produce as much weapons-grade plutonium as the United States produced. It would, however, allow China to manufacture approximately 68 new nuclear warheads each year, or about two-thirds of the number Richards claims China will add each year between 2027 and 2030. 

Assessing the scale of China’s nuclear buildup

Does that qualify as “breathtaking?” Does it require Congress to fund a US nuclear “capacity shift?” The United States currently has 5,428 nuclear warheads in its arsenal and enough weapons-grade plutonium to make many thousands more. China’s decision to enlarge its nuclear force is deeply disturbing and should be condemned.  But it is hard to see how it warrants urgent new investments in the US nuclear arsenal.

The current scale of the increase in the size of China’s nuclear arsenal does not suggest Chinese leaders are seeking nuclear parity with the United States. If they were, they could increase China’s stockpile faster by building reactors dedicated to the production of weapons-grade plutonium, which would not interfere with the operation of their civilian nuclear program and would be more reliable and much cheaper than fast breeder reactors.

As a nuclear weapons state under the Nuclear Non-Proliferation Treaty (NPT) China can make as much weapons-grade plutonium as it wants. It does not need to try to hide what it is doing by diverting plutonium from a civilian program. The Chinese government certainly made no effort to hide the new missile silos it is constructing in the deserts of Western China. US non-governmental organizations were able to find them using comparatively low-resolution commercial satellite imagery.

If China does divert plutonium from its civilian program, as Richard suggests is “highly likely,” it is an indication China may be trying to supplement its existing stock by a comparatively modest amount. A more ambitious and rapid expansion that would be genuinely “breathtaking” would be best achieved with a dedicated, and significantly larger, plutonium production program. 

Prevent defense

All the speculation about China’s stocks of plutonium and its potential enlargement could have been prevented by the early entry into force of a Fissile Material Cut-Off Treaty (FMCT). Drafts of the treaty include mechanisms for accounting for past production along with a verifiable ban on new production. Negotiations were a distinct possibility in the brief but heady days of progress in international nuclear arms control that followed the end of the Cold War. 

China was preparing for those negotiations in earnest. Participation in the negotiation of the Comprehensive Nuclear Test Ban Treaty (CTBT) left China with an accomplished team of technical experts and negotiators from the nuclear weapons labs, the military, and the diplomatic corp. I met many of them when I first started working for the Union of Concerned Scientists in 2002. The CTBT was the first and only international nuclear arms control agreement China helped to write. Chinese expectations the CTBT would be quickly followed by an agreement on fissile material were genuine. 

Sadly, those expectations were dashed after the United States failed to ratify the CTBT, restarted efforts to develop ballistic missile defenses and withdrew from the Anti-Ballistic Missile (ABM) Treaty. These and other counterproductive events, like the breakdown of exchanges between the US and Chinese nuclear weapons laboratories, helped push US-China cooperation on nuclear arms control into decades of stagnation. 

Both countries still claim to support negotiating an agreement on fissile material production. For those in the United States worried about the expansion of China’s nuclear arsenal, putting a verifiable end to Chinese weapons-grade plutonium production should have been, and still should be, their top priority.

Posted in: China, Nuclear Weapons

About the author

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Gregory Kulacki is an expert on cross-cultural communication between the United States and China. Since joining UCS in 2002, he has promoted dialogue between experts from both countries on nuclear arms control and space security.