Also related and worth a read, I think, is the Supreme Court case Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579 (1952). The content of the dispute is different, as it involves the President seizing private property, but it is (one of?) the seminal cases regarding the scope of presidential powers. Justice Jackson’s concurring opinion is, at least for now, considered the best articulation of when the President may take unilateral action.