North Korea has been having increasing problems smuggling weapons out (exports sold for hard currency) and in (for their own forces). The growing number of trade sanctions (because of the North Korean work on banned nuclear and ballistic missile programs) has resulted in more efforts, both by the United States and many other major trading nations, to detect and halt North Korea arms shipments.
To get around these obstacles North Korea has resorted to more sophisticated methods to get the illegal shipments in and out of the country. The latest scams make use of using air freight (literally, as in commercial air carriers) more frequently. This also involves in breaking the hardware into the smallest possible size and sending all the pieces via different carriers and different routes. North Korea has long used civilian “agents” in China to take stuff that is easily shipped by rail or truck from North Korea to China and then use forged documents to put it on aircraft to other “agents” in foreign countries who will eventually get it to the destination. The get stuff into North Korea the same routine is used, but in reverse. This scam is harder to penetrate, but means much higher shipping costs. These higher expenses the North Koreans simply consider a cost of doing business and well worth it if the entire shipment is not intercepted. If some parts are discovered and seized, they are easier to replace than the entire assembled item.
There is one area North Korea is not having problems exporting and importing. That is when the item is just tech. This is just data and that can be put on a fingernail size micro memory card (as used in cameras, smart phones and tablets). But often engineering samples (chemical or mechanical) are needed and this bulkier and often explosive stuff is easier to detect.