Did you think that they made it clear? All they said was that one Swiss official doubted the North Koreans could have done it based on the quality of actual North Korean currency.
If it is the North Koreans, it appears that they don't want to destabilize U.S. currency, rather just print enough hard currency to pay for Hennessey and Mercedes. They could easily have stockpiled OVI and other printing supplies (paid for with hundred dollar bills).
BTW, the Germans did counterfeit British currency during World War II and used it to pay off spies.
Actually they quote John Bolton, no liberal, as saying he never saw any evidence that North Korea actually manufactured the notes, though they were caught distributing them. Which would seem to support the idea that these notes were manufactured in order to distribute through certain channels and follow the paper trail. It could be that they're being used to identify links between terrorist organizations and rogue nations, certain individuals and terrorist organizations, things like that. Of course it that is the case then McClatchy newspapers have just torpedoed it.
BTW, the Germans did counterfeit British currency during World War II and used it to pay off spies.
Yes they did. But the currency of 60 years ago is nowhere near as high tech as currency now. They didn't have the embedded strips and the micro-printing used on today's notes.
The quality of actual North Korean currency? Remember that that country doesn’t have anything worth buying, even for its severely repressed subjects, not even food. And it’s the ultimate police state, so no one would dare counterfeit North Korea’s own worthless currency. North Korea also has a 100% tax on everything and generally doesn’t permit any sort of banking or other economic activity outside the government. You don’t need a sophisticated currency when it can’t buy any products or services.