Article 1 deals with Congress. From Section 8:
“1. The Congress shall have Power To...pay the Debts and provide for the common Defence and general Welfare of the United States...
11. To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water...
14. To make Rules for the Government and Regulation of the land and naval Forces;
15. To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;
16. To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as my be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress;”
Article 2 deals with the executive, and this is the sum total of what it says about his role with the military:
Sec 2 (1): “The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States.”
Congress has the major involvement in setting up how the military works, and the POTUS is simply to execute that. Congress provides for the common defense, and the way they have done that is through the NDAA, which gives authority for the military to determine if someone is an enemy combatant and to detain them BEFORE they can attack the country. If POTUS is the person who intends to attack the country - either directly or by aiding others to successfully attack the country - then the NDAA authorizes the military to detain him. Unless you can show me where in the NDAA Congress makes the POTUS a king with an absolute right to destroy the country unhindered.
Show me where that is, or else the NDAA authorizes ANY enemy combatant - including anybody within government - to be detained for the national defense of the country, which the Constitution places in the hands of Congress.
I am not talking about removing a POTUS, so the Constitution’s provisions for removing a POTUS is irrelevant. I am talking about national defense - protecting the country from its enemies wherever they may be found. And I just cited the Constitutional authorization for CONGRESS to do that, which they did in the NDAA.
If it involves charging the President with crimes, and convicting him, the only process is outlined like I said (per the US Constitution, the US House of Representatives and the US Senate). There is no process for arresting him.
And then, of the three branches of government - Legislative, Judicial and Executive - the Military is directly under the control of the Executive Branch, the President being the Commander in Chief. It’s the President that orders the military, not the military that orders the President ... :-) ...
That’s pretty much all you need to know in a nutshell.