According to a statement issued by the USA's Office of Foreign Assets Control (it's primary financial and economic sanctions department which also investigates and takes action in respect of breaches) says this "Between approximately March 26, 2015 and May 19, 2015, American Express Travel Related Services Company (“Amex”) issued a prepaid card to, and processed 41 transactions totalling $35,246.82 on behalf of, Gerhard Wisser,a Specially Designated National (SDN)."