European chips in Russian drones: sanctions evasion via China

What happened?

In May 2026, Ukrainian military intelligence recovered an STM32 microcontroller from STMicroelectronics from a downed Russian Geran-4 drone. According to TechRadar, the Ukrainian database recorded 270 STMicroelectronics components in Russian drones, missiles, and warfare systems as of that date, more than double any other European manufacturer. This finding is not an isolated case: since 2022, multiple similar incidents have been documented, such as Texas Instruments chips found in Russian Kh-101 missiles in 2023, or Intel components in navigation systems. However, the recurrence of STM32 chips, designed for industrial and consumer applications, underscores a systemic pattern in sanctions evasion.

The STM32 is a 32-bit microcontroller widely used in consumer electronics, automotive, and IoT due to its low cost and versatility. In a military context, it is used to control motors, process sensors, and manage communications in drones. The presence of this chip in the Geran-4, an Iranian-origin one-way attack drone, demonstrates how civilian components are integrated into lethal systems. The conflict in Ukraine has accelerated this trend: according to a 2025 report by the Royal United Services Institute (RUSI), Russia imported over $2 billion in dual-use electronic components between 2022 and 2025, many through intermediaries in third countries.

The supply route

The supply chain bringing STM32 chips to Russia is complex and opaque. STMicroelectronics designates Avnet, a Phoenix-based distributor, as a key partner for its STM32 line. Avnet operates a subsidiary in Hong Kong, which sold growing volumes of these chips to Shenzhen Hobbywing Technology, a Chinese manufacturer of drone propellers. Hobbywing's purchases rose from about $400,000 in 2024 to $1.95 million in 2025, according to international trade data analyzed by TechRadar. This increase coincides with the rise in Russian drone production, which went from about 100 units per month in 2023 to over 1,000 in 2025, according to estimates from the Ukrainian Defense Ministry.

Hobbywing uses STM32 chips to manufacture electronic speed controllers (ESCs), essential components for regulating drone motors. These ESCs are sold to Nanchang Sanrui Intelligence Technology, owner of the T-Motor brand, known for its high-performance drone motors and propellers. Sanrui declared purchases of over $7 million in controllers from Hobbywing in the first half of 2025 alone. Sanrui's subsidiary, Jiangxi Xintuo, was later sanctioned by the U.S. Office of Foreign Assets Control (OFAC) in December 2025 for exporting drone technology supporting the Russian military. Trade records show Xintuo shipped T-Motor products to at least six Russian buyers that were later sanctioned, including the Russian company SMT iLogic, linked to the Russian military-industrial complex.

This scheme resembles previous cases of sanctions evasion, such as the sale of AMD chips through distributors in Turkey and the United Arab Emirates for use in Russian air defense systems. However, the scale and sophistication of the Chinese network is greater: according to a 2026 report by the Center for Strategic and International Studies (CSIS), China has become the main conduit for dual-use technology to Russia, leveraging its dominance in civilian drone manufacturing.

Why it matters

This case illustrates how technology sanctions can be circumvented through complex supply chains and the principle of 'substantial transformation': components are integrated into new products before reaching their final destination, making legal tracing difficult. Samuel Bendett, a researcher on Russian military technology at the Center for Naval Analyses (CNA), notes that Beijing plays a key role in helping Moscow evade restrictions. 'China not only supplies components but also provides legal cover by transforming chips into finished products,' Bendett says. This process makes it difficult to hold original manufacturers like STMicroelectronics accountable, as chips are sold legally to authorized distributors.

Lilly Lee, a researcher at the Taiwanese think tank DSET, adds: 'The goal is not just to build Chinese drones... It is to ensure scale and strengthen a system that can absorb feedback from the real battlefield.' This implies that the civilian drone industry, inherently dual-use, is difficult to dismantle through sanctions. A 2025 Stanford University study found that 70% of electronic components used in Russian military drones come from civilian manufacturers, making sanctions ineffective without broader international cooperation. Additionally, the principle of substantial transformation is being challenged by legal experts, who argue it should be revised to close this loophole.

The market impact is significant: STMicroelectronics, which reported revenues of $17.3 billion in 2025, faces pressure to improve export controls, though its stock fell only 2% after the report's publication, suggesting investors do not anticipate direct sanctions. However, reputational risk is high, and the company could lose sensitive government contracts. On the other hand, Avnet, with revenues of $26 billion in 2025, has seen increased sales in Asia but could face restrictions if the U.S. tightens secondary sanctions.

Consequences

Sanctions have had little effect: Sanrui has identified new business partners and exports through 'Eastern European networks,' according to leaked internal documents. A website linked to Xintuo continues to sell T-Motor products globally and accepts credit cards with no apparent restrictions. Analysts warn that cutting one supply route rarely stops the flow of chips to battlefields. For example, after 2023 sanctions on Turkish distributors, routes shifted to Kazakhstan and Kyrgyzstan. In 2025, the volume of electronic component trade between China and Russia increased by 40%, according to the UN Comtrade Database.

'There is no direct way to stop it,' says Bendett, describing how dual-use components move through civilian trade networks. 'As long as there is demand, there will be intermediaries willing to take risks.'

The consequences for end users, both civilian and military, are profound. Russian drones equipped with these chips have caused civilian casualties in Ukraine, and the prolongation of the conflict depends in part on the availability of these components. For technology companies, the ethical dilemma is growing: how to ensure their products are not used for warfare? Some, like STMicroelectronics, have implemented blockchain-based traceability systems, but their effectiveness is limited when chips are integrated into third-party products.

What readers should know

• Current sanctions are insufficient to block the supply of European technology to Russia, as demonstrated by the persistence of STM32 chips in Russian drones.
• China acts as a key intermediary, leveraging its civilian drone industry to transform components and evade controls.
• Component traceability is lost once they enter the Chinese manufacturing chain, due to the principle of substantial transformation.
• Stricter international cooperation and stronger verification mechanisms are needed, such as joint audits and secondary sanctions on intermediaries.
• Consumers and companies should be aware that dual-use products can have unintended consequences and support supply chain transparency policies.

In summary, the case of the STM32 in Russian drones is not an isolated incident but a symptom of a systemic problem requiring multilateral solutions. As long as demand for dual-use technology persists, unilateral sanctions will have limited impact, and innovation in evasion methods will continue to outpace control efforts.