Apparently the US have been detaining European greencard holders, upon their return to the US after travels. Some have been deported to their countries of origin, some are held in prison in the US.
A French man has been rejected entrance into the country over him having messages on his phone criticial of Trump, he was sent back to France after overnight detention.
A German woman with a tourist visa was equally rejected and send back after overnight detention without access to her medication.
As of yesterday Denmark, the United Kingdom, Germany, Finland and Canada have revised their travel guidelines for the US.
This includes warnings over being denied entry despite a visa, detention and the US no longer recognizing the X gender marker in passports.