U.S. Army Gen. John Nicholson accused Russia of supplying arms to the Taliban last week in an interview with BBC News, saying Afghan leaders had delivered weapons to U.S. headquarters claiming they were given to Taliban fighters by the Russians.
Nicholson also said it was clear to him that the Kremlin is "acting to undermine our interest."
As NPR Pentagon correspondent Tom Bowman reported last year, it is not the first time that the four-star general has made the accusation. Last year, Secretary of Defense Jim Mattis also discussed the concern.
Nicholson confirmed the same assertion before the Senate Armed Services Committee last year:
"If Russia is cozying up to the Taliban — and that's a kind word — if they are giving equipment that we have some evidence that the Taliban is getting ... and other things that we can't mention in this unclassified setting? And the Taliban is also associated with al-Qaida? Therefore Russia indirectly is helping al-Qaida in Afghanistan," said [Florida Democrat Sen. Bill] Nelson.
"Your logic is absolutely sound, sir," Nicholson replied.
Russia routinely has denied the allegations, calling Nicholson's most recent statements "idle gossip".
"Once again, we insist that such statements are absolutely baseless and appeal to officials not to talk nonsense," the embassy said.
Officials in Russia have said they only have limited contacts with the Taliban and that they are aimed at encouraging peace talks and protecting Russian citizens.