I've read Aquariums of Pyongyang, Without You There Is No Us, Escape from Camp 14, and I think a couple others. Blood Brothers is now 20 years old and contains some gonzo shit but one of the allegations supported by everything else I've read is that North Korea's porous border with China facilitates North Korea's black market activity, which forms the fundamental basis of its economy. Both Aquariums and... some other book I can't remember the title of (Girl with Seven Names?) reference the human trafficking between North Korea and China, with many Chinese laborers in the 3rd world actually being North Korean.
Food shortages in North Korea have worsened in recent months, due in part to the border closures, according to international experts. Kim Jong Un in February called for a transformation in agriculture and stressed the need to hit grain production targets.
If the North Koreans are walling off their northern border, that means that the threat from interacting with the world is greater than the benefit of a semi-porous border. Cybercrime might explain the difference. Dunno.
Most of these fences are around river crossings. Escapee accounts of North Korean river crossings aren't dissimilar from Rio Grande river crossings between Mexico and Texas.
LOL like the North Korean government justifies anything