Which was my original point: war declarations have become meaningless in this day and age. Congress doesn’t even have to “fund a war” anymore. With a $1T annual defense budget, the President can pretty much do as he pleases with the military.
No, the President cannot “do as he pleases with the military.” Congress can terminate funding for a particular war or prohibit certain military spending and actions and the courts will enforce that unless the President’s core power as commander in chief is transgressed. Read the Supreme Court cases from the Vietnam era and you will see my point.