The provision of the Constitution giving the war making power to Congress was dictated, as I understand it, by the following reasons. Kings had always been involving and impoverishing their people in wars, pretending generally, if not always, that the good of the people was the object. This, our Convention understood to be the most oppressive of all Kingly oppressions; and they resolved to so frame the Constitution that no one man should hold the power of bringing this oppression upon us. — 1848

My Take – If the president has the ability to send troops to make war wherever and whenever he wants to, then he will start to assume the ability to use them to suppress dissent wherever and whenever he wants to.  The way it’s supposed to work is that the State Department fails in diplomacy, the President requests a declaration of war, and Congress votes on it.  If the war resolution passes both houses, then the President prosecutes the war under congressional oversight.

What seems to be happening recently is that the press sees something they find objectionable, they broadcast it far and wide at the top of their lungs, the President wants to look presidential, so he and the Secretary of State lambast it, play to the domestic and foreign markets, and eventually send in the Marines or Air Force so that they look like they’re in control of the situation.  Only rarely do they consider whether or not intervention is in the best interest of the United States, and only slightly more often do they go to Congress for even a milk toast authorization of force.  Every time they do it, they erode the power to declare war and constrain the President from waging war on a whim.