Accusing North Korea of forcing prisoners to mine coal for export.

Where does the exported coal go? China, I suppose. Few other countries would buy it.

There is no way to stop North Korea from exporting coal to China, and no way to pressure China from ceasing to buy it. But this becomes part of a bigger issue: China must stop burning coal! We can, and already do, put pressure on China to cut down and eventually cease its use of coal.

I don't know from the article whether the exported coal is thermal coal (burned for the heat alone) or coking coal (used to mix carbon into iron). That makes a difference, since the world needs to eliminate use of thermal coal, but it will not cease the much smaller use of coking coal.