Federal agents have begun questioning U.S. technology companies on how their computer chips ended up in Russian military equipment recovered in Ukraine.

Commerce Department agents who enforce export controls are conducting the inquiries together with the FBI, paying joint visits to companies to ask about Western chips and components found in Russian radar systems, drones, tanks, ground-control equipment and littoral ships, according to people familiar with the matter, who spoke on the condition of anonymity to discuss sensitive investigations.

“Our goal is to actually try to track that back, all the way back to the U.S. supplier” to determine “how did it find its way into that weapons system,” one Commerce official said of the probes.

“Just because a chip, a company’s chip, is found in a weapon system doesn’t mean we’ve opened up an investigation on that company,” the official added. “What we’ve done, though, is we’ve opened up an investigation on how that company’s chip got into that system.”

Many of the components appear to have been manufactured years ago, before the Russian seizure of Crimea in 2014 led the U.S. to tighten export restrictions. But others were manufactured as recently as 2020, according Conflict Armament Research (CAR), a research group in London that has examined some of the parts.

For years it was legal for companies to sell basic computer chips to Russian military entities without first receiving permission from the government, so pinpointing illegal sales requires determining the type of chip and date of sale. Tracing transactions can also be laborious because electronic components often travel through a chain of distributors before reaching the end user.

A lawyer representing one of the contacted technology companies said investigators for now are casting a “wide net,” looking at a variety of different chips and electronic components to track the paths they took to the Russian military.

Among the questions federal agents are asking: whether tech companies sold their products to a specific list of companies, including middlemen, that may have been involved in the supply chain, the lawyer said.

Russia manufactures few computer chips or electronics of its own, forcing it to rely on imports.

The United States for decades has tightly controlled sales to Russia of the highest-tech chips and those designed for military use, requiring exporters to obtain a government license. But sales of electronics below that threshold — including the kind commonly found in commercial products — were not widely restricted until 2014, when the United States began requiring exporters to obtain licenses before selling a broader range of chips to the Russian military.

Since Russia’s invasion of Ukraine in February, the U.S. and many allies have prohibited all chip sales to Russian military buyers, and placed restriction on chip sales to other Russian buyers in an effort to prevent the country’s armed forces from accessing western high-tech.

The federal probes come as researchers and security services from Ukraine, Britain and elsewhere report finding a host of Western electronics in Russian military gear damaged or abandoned in Ukraine.

CAR last month sent investigators to Ukraine to examine Russian weaponry and communications equipment and reported finding components from 70 companies based in the United States and Europe.

They found the parts in military radios, airborne defense systems and in remnants of cruise missiles that the Ukrainians recovered in various towns and villages, Damien Spleeters, one of the CAR investigators, said in an interview.

CAR for now is declining to name the Western companies involved, because it is still contacting them to request more information, Spleeters said.

Markings on two foreign-made chips that Spleeters examined showed that they were manufactured in 2019, he said.

“It’s significant for me because it shows that even after Russia took Crimea and the first package of sanctions were taken against them, they still managed to acquire critical technology, critical components for important pieces of equipment that they are now using against Ukraine,” Spleeters said.

Those chips, found inside two Russian military radios recovered in Ukraine’s Luhansk region, had some of their identification markings scratched out, suggesting that Russia “wanted to make it more difficult to find out who was involved in the chain of supply,” Spleeters said.

Another set of chips manufactured by Western companies between 2017 and 2020 were part of missile fragments that hit the southern Ukrainian city of Mykolaiv on March 29, Spleeters said. At the time, Russian forces were attempting to capture a broad swathe of Ukraine’s Black Sea coast.

CAR also examined Western-made chips manufactured between 2013 and 2018 that were part of a missile that landed in central Ukraine on Feb. 24, the first day of Russia’s invasion, Spleeters said.

The latest CAR findings follow a report from the group late last year that detailed Western electronics found in several Russian military drones.

A team from a separate British group — the Royal United Services Institute, or RUSI, a defense-focused think tank — also traveled to Ukraine recently to inspect Russian equipment and to review teardowns conducted by Ukraine’s military.

A single piece of radio-jamming equipment revealed computer chips from a dozen U.S. companies, including Intel, Analog Devices, Texas Instruments and Onsemi, according to a report RUSI published in April. The gear also contained components from half a dozen chipmakers in Europe, Japan and Taiwan.

The radio-interference equipment, named Borisoglebsk-2, was designed to interrupt the enemy’s communications and was likely manufactured around 2015 or later, Nick Reynolds, one of the report’s authors, said in an interview.

None of the Western chips was specifically designed for use in military equipment, according to two electrical engineers who reviewed the component list. The parts were developed for general commercial use, and many were relatively outdated, manufactured between 2000 and 2010, the engineers said.

“A lot of these components are very general purpose and could be used in wide range of devices,” said Peter Bermel, an associate professor of electrical and computer engineering at Purdue University. “Most of the items they are listing are available through any commercial computer parts supplier or digital parts supplier.”

“A non-trivial fraction of these parts are now considered obsolete by the manufacturers,” Bermel added.

Reynolds, a research analyst for land warfare at RUSI, said Russia’s technical demise in recent decades, partly sparked by a large post-Soviet brain drain, has forced it to use Western chips. “Its defence industry has struggled to attract and retain talented young engineers, who have often chosen to move abroad instead,” Reynolds said by email.

Intel spokesman William Moss said that for over a decade, all of the company’s “sales in Russia have been through distributors who are responsible for complying with applicable laws, including U.S. export controls.”

“Intel has suspended all shipments to customers in both Russia and Belarus, and Intel will continue to comply with all applicable export regulations and sanctions,” he added.

Onsemi, a chip company based in Phoenix, said it stopped producing one of the chips found in the Russian equipment in 2008. The chip was “designed for a variety of uses in commercial products,” spokeswoman Stefanie Cuene said, adding that the company complies with U.S. export controls and currently does not sell any products to Russia or Belarus.

Texas Instruments “complies with applicable laws and regulations” and “is not selling any products into Russia or Belarus,” spokeswoman Ellen Fishpaw said.

Analog Devices, the company behind more than a dozen of the components found in the Russian equipment, didn’t respond to requests for comment.

The RUSI researchers also reported inspecting a U.S.-manufactured component that the Ukrainian military found inside a Russian 9M949 guided rocket. The rocket uses the component — a type of electronic device called a fiber-optic gyroscope — for navigation, RUSI said.

The British researchers declined to name the U.S. company that made that component, saying RUSI was continuing to research that and other parts.