Satellite imagery of North Korea’s Tumangang Rail Facility at the border with Russia reveals an unprecedented number of freight railcars, totaling approximately 73. This level of rail traffic is much higher than previous years, even before the pandemic. The use of tarps to cover the shipping crates and equipment makes it difficult to determine the exact contents being transported. However, given recent discussions between Kim and Putin regarding military exchanges, it is likely that North Korea is supplying arms and munitions to Russia. This would violate UN Security Council resolutions and could result in additional sanctions. Furthermore, the construction and upgrades at the facility suggest that North Korea intends to expand its capacity at this border crossing.
https://beyondparallel.csis.org/dramatic-increase-in-dprk-russia-border-rail-traffic-after-kim-putin-summit/