Credible explanation. But, Japan could carry these certificates in via diplomatic pouch, take them to the Swiss bank and wheel and deal away. Why use the Sandy Burglar method?
You have a good idea there..... Perhaps because dipsticks talk too much? The Jap Dips have one agenda and the BOJ or Ministry of Finance have another? Maybe Japan needs to raise some quick cash?
We defend Japan and they buy our Treasuries. You never hear about Japan abandoning the USD but you hear that about China. So if Japan wants to dump US Treasuries undetected they would do it through an unexpected route. Switzerland.
Just my speculation
China could also want to dump USD quietly. An orderly exit