Coal has started to pile up at a Russian-operated pier in North Korea for the first time in over four years, according to NK Pro analysis of satellite imagery, in what could signal the restart of a key joint project between the two countries.

The pier is located in northeast North Korea at the south end of Rason port, next to other piers that the two countries are actively using in an apparent weapons transfer scheme that started last August. 

A revival of the coal port could help further expand Russia-DPRK economic ties and give