North Korea has reportedly begun transferring artillery to Russia.

Quoting a U.S. official, CBS News reported on Thursday that it was not clear whether the transfer is part of a new, long-term supply agreement or a more limited consignment, or what North Korea is getting in return.

The reported arms assistance by the North appears to be the result of a summit between North Korean leader Kim Jong-un and Russian President Vladimir Putin during Kim's rare trip to Russia last month.

Putin hinted after the summit that he and Kim had discussed military cooperation, and that cooperation appeared to be taking shape this week.

KBS asked the U.S. Department of Defense to confirm the report, but the Pentagon said it has nothing to add other than the past remarks by its spokespersons.

Officials of the Biden administration, including the Pentagon, have noted that any arms deals between Pyongyang and Moscow would be a violation of UN Security Council sanctions, warning that North Korea would have to pay a clear price for such deals.