transactions with Iran...check out the attached link which shows how it all began.
BTW, how much would you be 'willing to pay' to ensure you could get IAEA experts on the ground in Iran along with effective agreements and measures for monitoring their nuclear facilities?...you know...keep them from developing a nuclear weapon?...what would be the 'downside'...financially...for the the whole world, if Iran ended up with nukes?...$1.7B of justly owed money to Iran for that objective is a rounding error to what we've spent on other foreign policy issues in Afghanistan, Ukraine, etc.
C'mon, Ned...you're an attorney...you should have a sense of how to arrange a 'prudent' deal that accomplishes your fundamental objective.
Link: https://www.brookings.edu/blog/markaz/2016/10/03/the-united-states-iran-and-1-7-billion-sorting-out-the-details/