The US says North Korea will continue supplying weapons to Wagner Group mercenaries in Ukraine - as it released an image it said showed a shipment of rockets and missiles being collected.
North Korea has previously denied the claims as has Wagner owner Yevgeny Prigozhin, who last month called it "gossip and speculation".
The White House said the satellite image was taken on 18 November and showed a Russian train travelling to North Korea to collect the arms.
"On November 19, North Korea loaded the railcars with shipping containers, and the train returned to Russia," said White House national security spokesperson John Kirby.
"While we assess that the amount of material delivered to Wagner has not changed battlefield dynamics in Ukraine, we expect that it will continue to receive North Korean weapons systems," he said.
Tougher sanctions will also be imposed against the Wagner Group and its global support network next week when the US declares it an Transnational Criminal Organization (TCO), Mr Kirby added.
This will freeze any assets it has in the US and ban Americans from providing funds, goods, or services.
Mr Kirby said: "With these actions, and more to come, our message to any company that is considering providing support to Wagner is this - Wagner is a criminal organisation that is committing widespread atrocities and human rights abuses, and we will work relentlessly to identify, disrupt, expose, and target those assisting Wagner."
He estimated that the private security company has about 50,000 personnel fighting alongside Russia troops in Ukraine - 40,000 of them convicts signed up from Russian prisons.
It has been particularly active in the fighting in Bakhmut and Soledar in eastern Ukraine and the White House is growing increasingly concerned about its involvement.
Russia's defence ministry also has reservations about Wagner's recruitment strategy but the US believes it will continue to recruit prisoners, Mr Kirby added.
Sky News has visited a cemetery for Wagner mercenaries in southern Russia and saw row after row of identical fresh graves - an indication of the deaths the group is suffering. Ukraine says thousands have died.