First, the military can and has operated within the geographic boundaries of the United States in the War of 1812, the Mexican-American War and the various Indian wars. Eisenhower deployed the 101st Airborne to protect the Little Rock 9, and federalized the Arkansas National Guard (which is a militia in Constitutional speak). LBJ federalized the Alabama National Guard to enforce the Civil Rights Act. Those are instances I can think of off the top of my head where the military was deployed domestically. I'm sure there are others. The point is you are hung up on foreign versus domestic actors for no particular reason other than convenience.
This leads us to 10 USC 251, 252 and 253. In particular, Section 252 grants the President authority to use the military when unlawful obstructions "against the authority of the United
States, make it impracticable to enforce the laws of the United
States in any
State by the ordinary course of judicial proceedings...." You do not seem to dispute that Article II vests the president with all executive power, including that of the commander in chief. 18 USC 2384 criminalizes seditious conspiracy. Seems like ole Joe would have no problem determining that Trump advocated overthrowing or destroying the government on January 6 and afterward with his own rhetoric and nonsense, which would fall under 18 USC 2385. Since you've decided that Trump will implement Project 2025 there's that too. I suspect there are other statutes that could be applicable as well.
I interpret "justified" to mean carry out an official act which would be immune under the recent Supreme Court decision.
So pull that trigger Joe. But, of course, it's all BS. Biden does not believe Trump is a threat to democracy. But even in his diminished state, ole Joe is certainly opportunistic enough to stoke fear for votes.
Only in EXTREME EMERGENCIES, can the USA President EXTREMELY TEMPORARILY use the actual non national guard, actual Army, Airforce, Marines(Not Airforce national guard, not army nation guard(those are not part of the actual military forces, and are there for the protection of the country, domestically, available at the beck and call of Governors, USA president for domestic problems, and unlike the actual military, Army, Airforce, Marines, is not restricted to temporaryness domestically, and doesn't need to have the congress, sanction, approve, etc, after the temporaryness expires, like what has to happen in with the army, Airforce, marines, navy, domestically. The national guard can also be called up and used in wars overseas. The national guard can regularly help with law enforcement, etc, domestically. The Army, Airforce, Marines, Navy, can only help with Law enforcement domestically, IF IF IF it's only for a short period of time temporarily, and only if it's a extreme emergency, and only if the police, ATF, DEA, FBI, CIA, NSA, are not capable of handling, dealing with the emergency. And then after the time limit is up, then Congress has to approve the use of the militiary domestically. The National Guard doesn't have that, those restrictions, which is why see national guard more often used domestically, then the Militiary, Army, Airforce, Marines, etc.)
The constitution says that the Militiary, Army, Airforce, Marines, etc, con only be used domestically in the most extreme of emergencies, and only is Police, Federal Marshall's, DEA, ATF, FBI, CIA, National Guard, etc, are not able to deal with the problem. And if the Militiary, Army, Airforce, Marines, etc, are authorized domestically by USA president, it's only temporary, and if it last beyond temporary, the congress has to approve it.
Examples of this, is George Washington calling up the continental Army as President to deal with Farmers rioting(back then law enforcement didn't have the enforcement abilities that law enforcement has now, so George Washington had to use the continental army(Not National Guard). If George Washington had wanted to keep using them beyond the temporary situation, George would have had to get approval of congress.
Abraham Lincoln called up the armed forces(not national guard, militias, etc), to domestically deal with South Carolina firing on Fort Sumter. The Congress had to approve, and approved what Abraham Lincoln was doing. Thats why Abraham Lincoln had to have the victories at Antietam, Gettysburg, etc, because if those had been defeats, then the Congress would have likely to have revoked the authorization of the use of armed forces domestically, and Abraham Lincoln would have had to use the local law enforcement to try to stop the confederate armed forces, if the Congress had revoked authorization.
It's ultimately extremely ultimately extremely rare for the president to use the Army, Airforce, Marines, Navy, domestically, and if do that, have it last beyond temporary, and if last beyond temporary, rare for the Congress to approve it, etc. And part of the reason it's so rare nowadays, is that almost always the Police, SWAT, Marshalls, Homeland Security, FBI, CIA, NSA, National Guard, etc, are almost always able to deal with whatever happens domestically.
And that's as it should be, because the founding fathers, constitution, Bill of Rights, Declaration of Independence, Federalist Papers, Founding Documents, etc, are against the military, army, marines, etc, being used domestically, because might trample on individual rights, state rights, etc, and so they decided to only allow it, if local law enforcement, local militias, National Guard, etc, couldn't handle it, and only for a short, temporary period, and after that, only if Congress approved it.
They wanted to make it almost impossible to have the military, be involved domestically, and the constitution reflects that, and because of that, the constitution is generally against the military being used domestically, unless the rare, couple, few exceptions to the general forbidding the military from being involved domestically exist.
Those exceptions do exist, and under those exceptions the USA president can temporarily involve the military in domestic matters, but all other times it's FORBIDDEN to involve Militiary, Army, Airforce, Marines, etc, by, under the USA Constitution, the Supreme law of the land, and no other USC(United States Codes, laws), apply, as they are UNCONSTITUTIONAL IF IF they go against the constitution, and allow the President to wily, nilly use the militiary, army, Airforce, Marines, wily, nily, whenever he wants.
A example of USC(Codes, laws)being wrong, etc, there is a USC code, law, that forbids the burning of the USA flag. The Supreme Court has ruled that USC code, law, as unconstitutional, and has struck it down
Also there have been a couple, few past president's who have illegally used the militiary domestically beyond temporaryness, and where congress didn't authorize it, or didn't continue to authorize it, and where the president didn't stop, didn't follow the laws, constitution, and kept using the militiary illegally, domestically, where they were threatened with impeachment, removal(they were NOT impeached, removed, but they were threatened with impeachment, and people, congress, politicians, etc, threatened to impeach them.)
Now that applies to the militiary, Army, Airforce, Marines, etc. The NATIONAL GUARD IS, CAN BE USED DOMESTICALLY WITH A LOT MORE FREEDOM, LESS RESTRICTIONS, ETC, BY GOVERNORS OF STATES, AND BY THE USA PRESIDENT.
That's why we see the National Guard on a regular, consistent basis being involved domestically, on a regular, consistent basis.
So you accidentally misrepresented things a bit there DGibbs.