Travel Advisory - Trump blocks re-entry to the US for all citizens of certain Islamic majority nations. This ban impacts everyone from student visa holders to Legal Permanent Residents (Green Card holders). There are signs that Trump may lift the ban on Green Card holders, but there are also reports from around the world that Green Card holders have been prohibited from boarding flights to the United States.
If you or one of your parent's was born in or claims citizenship from any of the following countries you should not leave the United States until you have spoken with an immigration attorney as you may be locked out of the United States for the foreseeable future:
Here is an depth article on what we know and don't know as of this time.