That requires tax payer obligation. However "american taxpayer" is a well defined status reflected in laws and regulation which you may or may not have, even if you are paying US taxes regularly.

If you do have "american taxpayer" status, banks outside the US (essentially all of them these days) will refuse to let you do anything other than keep a checking and saving account, and brokers will refuse to do business with you, thanks to SEC regulations that say that only SEC regulated brokers and banks can handle securities on behalf of US taxpayers.