Any report that claims “Posse Comitatus” with regard to this is fake news.
It’s one thing to prevent the Army and Air Force (only services mentioned in the statute as prohibited) from conducting law enforcement with regard to US CITIZENS, but nothing prevents the US Military to defend the territorial integrity of the nation against a foreign invader.
That’s what I thought. Good to know.
There is ample SCOTUS precedent which states that until you have cleared customs and immigration you are not technically in the United States, and constitutional protections do not apply.
This is how ICE gets away with invasive examinations of laptops and cell phones at border posts.
So as long as the migrant has not cleared customs it would seem he is technically not here, and they can do what they want with him.
In fact, it is required.