The essence of the Korean story—how it originated and evolved since World War II—has been utterly distorted. Ironically enough, among the six key parties—the two Koreas, the U.S., China, Russia and Japan—it’s the U.S., the perennial ‘fall guy’ on this issue, that has by far the most positive story to tell. ...
The offering of security assurances would provide an opportunity to refresh and develop an important piece of the puzzle. Such assurances would offer every state directly associated with security on the Korean peninsula to make a substantive contribution to the sort of positive atmosphere needed to find a way into the core issue: opening up the path that leads to a peninsula that is both reliably stable and not a focus of major-power competition.
I'm just a simple unfrozen caveman blogger, but four-party assurances on the nuclear issue by America, Britain, Ukraine, and Russia to get rid of Ukraine's nukes in exchange for security guarantees (the 1994 Budapest Memorandum) did not prevent Russia from changing their mind once Ukraine had no nukes and invading Ukraine in 2014 to take control of Crimea and the eastern Donbas.
Sure, that older failure is not guarantee that a new deal will fail. Although who could blame North Korea if they don't want to be involved in a reboot of the Ukraine role?
Adding two more states--including one that proved untrustworthy on the very formula we are supposed to try--seems unlikely to be the path to success.