Russia is doing so in a country where, most military officials agree, the Afghan government and the Taliban are at a stalemate. As recently as two years ago, Russia engaged publicly with the Afghan government—going as far as to discuss arms sales, as well as logistical support for its police and armed forces. But more recent reports suggest Moscow is finding common cause with the Taliban. By engaging with the Taliban, Russia would have leverage with the largest non-state actor in the country—a group that is also supported by Pakistan. Indeed, Russian, Pakistani, and Chinese officials met in Moscow last December to discuss Afghanistan, a meeting marked by the absence of any Afghan government representatives or their allies from India. (A subsequent meeting was arranged to include those two nations and Iran.)

The Taliban and Russia may have made common cause over their shared opposition to the Islamic Movement of Uzbekistan and ISIS, both of which operate inside Afghanistan. Besides returning to prominence in the region, Moscow’s goal in Afghanistan, as it is throughout the Muslim world, is to limit the impact of the Islamist groups. So it’s incongruous for Russia to support the Taliban—unless it sees that group as helping keep the others in check without threatening Russia itself. But while Russian links to the Taliban can be alleged through news reports and public statements, direct Russian arms supplies to the Taliban are hard to prove.

Matt Schroeder, a senior researcher at Small Arms Survey, which tracks illicit weapons transfers, told me in an interview that many of the weapons seized or documented in Afghanistan are old—sometimes going back decades. This means that, even if Russian-supplied weapons are flooding the Afghan battlefield, they didn’t necessarily arrive recently—and could be traced back to the Soviet occupation.

“It wasn’t just Warsaw Pact weapons,” he said of the Cold War-era alliance of Communist countries established as a counterweight to NATO. “There was a lot Chinese, some were Pakistani.” Documenting any linkage to Russia is difficult, he said, and documenting any linkages to the Russian government would be even more difficult. “You really need a level of detail,” Schroeder said. “You need documentation. You need evidence that is very, very hard to come by.”

Thomas Ruttig, co-director of the Afghanistan Analysts Network, told me in an email that while Russia might be quite happy to see the 16-year-old U.S. mission in Afghanistan fail, tracking arms supplies to the militants is nearly impossible.

“Are there Russian contacts with the Taliban? Most likely,” he said. “This is not that difficult to arrange, for anyone.”

Ruttig pointed out that many of Russian officials during the Soviet occupation are prominent players today, as well. “It seems clear that Russia would not be unhappy to see the U.S. and the West fail in Afghanistan—as they, in the USSR incarnation … failed there in the 1980s,” he said. But of the weapons the Russians are said to have supplied the Taliban, Ruttig said “Russian-made weapons of those calibers can be obtained in many places.”

The U.S. claim—including those made in news reports—comes with no accompanying evidence, and the experts I spoke to said none of the open-source information they have seen suggest there is a direct link. But, as Schroeder said, “The U.S. government—they don’t tend to make claims like they did without some type of evidence, so I wouldn’t discount the possibility, but to independently corroborate those claims is very, very difficult.”