Article 1, Section 8
Before he (POTUS) enter on the Execution of his Office, he shall take the following Oath or Affirmation:—“I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States.”
Article 2, Section 2
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;
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U.S. ConstitutionWhat part of the Constitution says, oh, and the Capitol Building, Congress, and the VP -- they have their own separate security and aren't covered by the Constitution?