I did not see it. Ill have to go and look. Sorry, this is really long. 
I did look into the National Guard. Yes, the President can call them up and send them anywhere he deems fit.
First is the question of legality of using the military as a police force in the US. The Posse Comitatus Act.
www.brennancenter.org/our-work/research-reports/posse-comitatus-act-explained
The article states:
"“Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the Air Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both.”
In practice, this means that members of the military who are subject to the law may not participate in civilian law enforcement unless doing so is expressly authorized by a statute or the Constitution."
Right now the debate between the camps is this, is rounding up and detaining immigrants as police act or not? Trump says no, dems say yes.
On a side note, The Illegal Immigration Reform and Immigrant Responsibility Act of 1996 added Section 287(g) to the Immigration and Nationality Act, a provision that authorizes ICE to enter into agreements with state and local law enforcement agencies to allow select, properly trained officers perform immigration law enforcement functions under the supervision of ERO officers.
This would be an interesting court case I hope I never have to see.
The National Guard does not fall under the act unless they are called into Federal Service. So if Trump calls them up, the fall under federal service and the act applies to them.
Anyhow, back to the border and my opinion only on it. Take that for what its worth because he is so unpredictable.
I think he is posturing and hope he has no plans to escalate. I pray that is the case.
But Mexico and Canada should be worried here, as well as Panama. The amount of troops being sent to the border is clearly an over reaction, based on the low numbers of people he is actually deporting, which is below Bidens weekly numbers last I looked.
Based on his instability, I would be taking this very seriously if I were Canada and Mexico. And I know they are. But I also think Americans need to take this very seriously, because numbers of soldiers like this can keep people in just as easily as they can keep people out.
Especially since Trumps billionaire buddies have issued a proposal to build "processing camps" on military bases, which includes a fleet of small planes and a "small army" of private citizens empowered to make arrests.
After they run out of migrants, they will turn on LGBTQ people next. Someone has to keep those privately run prisons and camps making a profit.
www.politico.com/news/2025/02/25/documents-military-contractors-mass-deportations-022648