|Series 2006, top, later versions, bottom|
The November, 2017 South Korea sighting of the first banked 2006 Supernote is instructive, because conclusive identification of that note was only accomplished after a team of bank technicians experienced with counterfeits pored over the bill at length. This means that traditional techniques could fail to spot the bills as they are deposited.
We have a report from Singapore, where multi million dollar lots of the new Supernote are currently being offered to criminal syndicates, at the cost of fifty cents for each one hundred dollar face value. We have confirmation that the notes offered are indeed Series 2006. Previously, North Korea passed the Supernote through its embassies abroad, taking advantage of the diplomatic immunity granted to deliveries of DPRK goods to its Embassies, such as the one in in Singapore.
A number of the more advanced anti-counterfeiting features were not introduced until after 2006; they include raised 3-d printing, the bell hiding in the inkwell, and pale blue background color. Apparently these were impossible to duplicate, so the counterfeiters chose to rely upon the last series without enhanced protection, the Series 2006. Needless to say, these are bills ostensibly printed more than a decade ago, but the counterfeits are in mint, uncirculated condition.
We cannot say why the US Secret Service, which has jurisdiction over counterfeiting of American currency, or any other regulatory or law enforcement agency, has failed to publish a warning on the 2006 bill, but I would advise banks to seriously consider taking steps to block deposits of that series, both at the teller window, and at an Automatic Teller Machine (ATM).