if it were up to me, I would reprint all the $100 notes in a new design, in flashy red and pink colors, then tell the whole world anyone who does not exchange their old notes by 31 days will be left with dud notes of zero value which will not be honoured by the US government or financial system. Anyone coming in to exchange their old notes would need to provide ID and bank details and be registered with the IRS. Then all those notes held by the Russians would become worthless and all those held by chinese spys would be trash and all those held by drug barons in south America will be only good for burning. and all those countries trading in US dollars because they won't honor their own money, And all American business's that have dumped billions in $100 dollar bills in safes in foreign countries will be either exposed or left with nothing. Any foreign bank that tries to trade in its old notes will have to provide a full customer accounts list to the IRS and where the funds were obtained, if the identity of the customer cannot be found through legit means the funds will not be exchangeable. This would also apply to US citizens claiming social security but with billions hidden under their beds, or gangs laundering money. America hit the reset button on the greenback. if it were up to me.