Other customers include Iran, Syria and Pakistan.
I keep going back to a Nicolas Eberstadt piece cited here and this wonderful quote:
North Korea’s leadership, however, evidently entertains the concept of a “self-sustaining” defense sector — implying that Pyongyang views its military activities as generating resources rather than absorbing them. In the enunciated view of Pyongyang’s leadership, the dprk’s military sector is the key to financing the recovery of the national economy.
It does not require a great deal of imagination to spell out the operational details of this approach. While forswearing any appreciable export revenues from legitimate commerce with advanced market economies, North Korean policy today seems to be banking on the possibility of financing state survival by exporting strategic insecurity to the rest of the world. In part, such dividends are derived from exports of merchandise (e.g., missile sales, international transfer of wmd technology). But these revenues also depend heavily on what might be described as an export of services: in this case, military extortion services (or, perhaps better yet, “revenue-sensitive threat reduction services”) based upon Pyongyang’s nuclear development and ballistic missile programs.
This "business" needs to be put out of business.