Since the US cannot stop Americans from buying ICO's which they are clearly pushing from what many have reported the next logical thing is to go after is the exchanges that service Americans. Try to get a bank account outside the US. The legalities are daunting! You may not see a pattern here, but I mentioned IOTA in this bitfinex report because this exchange is the most well known location too purchase IOTA . Which so happen to be on many people scope at the moment.