It's not vague at all. Right-wing pundits are misinterpreting a key phrase.
What is Birthright Citizenship? Birthright citizenship is a legal principle under which citizenship is automatically granted to individuals upon birth. There are two forms of birthright citizenship: ancestry-based citizenship and birthplace-based citizenship. Birthplace-based citizenship, which...
www.americanimmigrationcouncil.org
The key portion :
"....
and subject to the jurisdiction thereof, are citizens of the United States and of the state where they reside."
.... of this line in the 14th Amendment :
"All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the state where they reside."
.... is being misapplied by the right. That phrase was included as a clause to exclude the children of diplomats, who have diplomatic immunity from criminal prosecution, and are therefore not covered under birthright citizenship and Native Americans who have been granted legal sovereignty. The right-wing wants to apply it towards illegal immigrants and non-permanent residents as well. However, those people are subject to criminal prosecutions if they violate American laws.
Now, I don't have a problem with ending the practice of so-called "anchor babies," but that will have to be done by way of a Constitutional Amendment. Trump's executive order doesn't have a prayer of holding up under judicial scrutiny.