A senior American General says Russia is not only supporting the Taliban in Afghanistan, they may also be supplying them.

FOX's Lucas Tomlinson has more from the Pentagon:

The top U.S. General in Europe says he sees evidence Russia might be supplying the Taliban in an effort to undermine the United States. This marks a significant turning point in Afghanistan.

Until now, the Pentagon said Moscow has only been influencing the Taliban to counter NATO. Army General Curtis Scaparrotti, the Supreme Allied Commander of NATO, made the startling revelation on Capital Hill Thursday.

This comes as the Taliban continue to capture territory in Afghanistan. The district center in Sangin in southern Afghanistan's volitile Helmand Province fell to the Taliban Thursday.

Last month, the head of U.S. forces in Afghanistan called the war a stalemate. Hundreds of U.S. Marines were killed in Helmand fighting the Taliban.

Now 300 Marines will return there this spring to relieve an Army unit. The first time, the Marines have deployed to Helmand since 2014.

At the Pentagon, Lucas Tomlinson, FOX News.

Follow Lucas Tomlinson on Twitter: @LucasFOXNews