Chinese authorities reportedly used US semiconductor technology subject to export restrictions to advance nuclear weapons research.
China's Academy of Engineering Physics (CAEP), the state-backed agency responsible for developing and maintaining the nation's nuclear weapons, has reportedly relied on Intel and Nvidia silicon for at least two years despite being placed under a US trade ban over a quarter of a century ago. According to Wall Street Journal investigation, the CAEP has likely used back channels and shell companies to obtain US chips for use in nuclear weapons simulations and other applications. The agency shares much in common with the US Department of Energy, as both are tasked with the development and maintenance of their respective nations' strategic weapons stockpiles. Since underground nuclear weapons tests were banned in 1996, such work has often been conducted using supercomputers designed to simulate various aspects of nuclear weapons testing.
In an effort to prevent US chips from being used for military applications, the US added the CAEP to the Commerce Department's Entity List in 1997, prohibiting the organization from importing certain technologies. However, the Journal's investigation revealed these efforts have proven largely ineffective. The findings uncovered more than 30 papers published by CAEP researchers that made use of American semiconductors, several with direct military applications. More broadly, a previous WSJ investigation found that the US approved 94 percent of licenses required to export restricted goods to China, underscoring the ineffectiveness of US Commerce Department measures.
The core problem is that US export bans restrict the sale of goods only to specific entities, usually those with ties to foreign militaries, while the restricted goods themselves are widely available in servers and PCs sold in the Chinese market. This creates opportunities for shell companies owned by the Chinese government to circumvent export controls. Adding to the challenge, many gaming-focused graphics cards share the GPU die used in chipmakers' datacenter products. For example, the GTX 1080 TI, one of the GPUs used for CAEP research, shares the same die as Nvidia's datacenter-focused Tesla P40, with only minor differences in memory, clocks, and shader counts. Similarly, Nvidia's RTX 4090 shares the same GPU die—the AD102—as its L40 accelerator.
Recent US Commerce Department actions have intensified pressures on China's access to advanced chips. In October, the Department revised its Entity List, adding more than two dozen Chinese firms and imposing generalized restrictions on AI chips and accelerators, including Nvidia's A100 and AMD's Instinct MI250. These measures reportedly caused problems for Chinese GPU vendor Biren, which relies on TSMC for manufacturing; the startup retooled its design, capping the chip's transfer rate to 576GBps, down from 640GBps, to avoid scrutiny. Nvidia employed a similar strategy, rereleasing its A100 as the A800 with a narrower memory bus to circumvent export bans.
While CAEP has long held a place on the US Entity List, many Chinese supercomputing centers had not faced the same restrictions. The National Supercomputing Center in Guangzhou province, home to the number 10-ranked TianHe-2 supercomputer on the Top500 ranking, was only added to the Entity List in 2015, after the US became aware the Intel-based system had been used in "nuclear activities." The US Commerce Department subsequently added a slew of other Chinese supercomputing centers to the Entity List in 2021 over suspicions the systems were being used by China's military actors to support military modernization efforts and nuclear weapons programs.