Satellite photos of North Korea’s Rajin port have detected signs of possible arms trading between North Korea and Russia.

The Voice of America (VOA) reported on Sunday that satellite photos of the port taken last Thursday by Planet Labs, a U.S. commercial satellite imaging company, showed a 110-meter-long large vessel at the port.

The photos reportedly showed a large crane used for moving containers standing in front of the vessel docked at one of three piers at the port.

The VOA said that a large vessel over 100 meters in length was first observed there on August 26, and three more were seen until October 14, adding that at least four large ships were observed in and out of the port over some 40 days, with hundreds of containers moved.

The report said that these vessels stayed at the port for one to three days to load the containers, but it cannot be concluded that these movements were for arms deals.

Earlier, the White House said that North Korea may have sent military equipment and ammunition to Russia through the port.

John Kirby, White House National Security Council coordinator for strategic communications, said on Friday that North Korea delivered more than one-thousand containers of military equipment and munitions to Russia last month for use in Ukraine.