Let’s review. This is from the Constitution (section 8):

The Congress shall have power …

To define and punish piracies and felonies committed on the high seas, and offenses against the law of nations;

To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water;

To raise and support armies, but no appropriation of money to that use shall be for a longer term than two years;

To provide and maintain a navy;

To make rules for the government and regulation of the land and naval forces;

And this is from 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

And that’s all it says about presidents and war powers. This is a bit of commentary from the Cornell Law School website:

The purely military aspects of the Commander-in-Chiefship were those that were originally stressed. Hamilton said the office “would amount to nothing more than the supreme command and direction of the Military and naval forces, as first general and admiral of the confederacy.” Story wrote in his Commentaries: “The propriety of admitting the president to be commander in chief, so far as to give orders, and have a general superintendency, was admitted. But it was urged, that it would be dangerous to let him command in person, without any restraint, as he might make a bad use of it. The consent of both houses of Congress ought, therefore, to be required, before he should take the actual command. The answer then given was, that though the president might, there was no necessity that he should, take the command in person; and there was no probability that he would do so, except in extraordinary emergencies, and when he was possessed of superior military talents.”

Of course, over the years the respective war powers of Congress and the President have been fudged and fudged and fudged some more.

The War Powers Act of 1973 says,

The constitutional powers of the President as Commander-in-Chief to introduce United States Armed Forces into hostilities, or into situations where imminent involvement in hostilities is clearly indicated by the circumstances, are exercised only pursuant to (1) a declaration of war, (2) specific statutory authorization, or (3) a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.

Dahlia Lithwick provides background on the War Powers Act here.

Now, here’s my question. Last month Congress passed a directive calling for Trump to withdraw U.S. support for the Saudi-led war in Yemen. It directs the “president” to remove U.S. armed forces from hostilities in or affecting Yemen within 30 days unless further engagement is authorized by Congress. The directive failed to pass with a veto-proof majority, and Trump vetoed it yesterday.

Trump saw the resolution as a personal assault on his authority, adding that the resolution would hurt military efforts abroad.

“This resolution is an unnecessary, dangerous attempt to weaken my constitutional authorities, endangering the lives of American citizens and brave service members, both today and in the future,” Trump said in a memo to the Senate signaling his veto.

Except he doesn’t have any constitutional authorities where war is concerned. And it seems to me that Trump cannot lawfully continue whatever he’s doing in Yemen now that Congress has told him to stop.

The US helps the Saudi-led coalition, which also includes the United Arab Emirates and several other Gulf Arab and African countries, by providing them with intelligence, selling them arms and ammunition, and, until late last year, fueling warplanes.

Granted, one could argue that the U.S. is not technically waging war in Yemen, but it is aiding other countries to wage war. However, about a year ago the New York Times reported that

about a dozen Army commandos have been on Saudi Arabia’s border with Yemen since late last year, according to an exclusive report by The Times. The commandos are helping to locate and destroy missiles and launch sites used by indigenous Houthi rebels in Yemen to attack Saudi cities.

This involvement puts the lie to Pentagon statements that American military aid to the Saudi-led campaign in Yemen is limited to aircraft refueling, logistics and intelligence, and is not related to combat. …

… In at least 14 countries, American troops are fighting extremist groups that are professed enemies of the United States or are connected, sometimes quite tenuously, to such militants. The Houthis pose no such threat to the United States. But they are backed by Iran, so the commandos’ deployment increases the risk that the United States could come into direct conflict with that country, a target of increasing ire from the administration, the Saudis and Israelis.

And what more do we not know?

Support for the Saudi-led forces began under the Obama Administration, and I believe that support was a huge mistake. But Trump deployed the commandos, apparently without consulting Congress, since it took a congressional investigation to find out about it. Both the Obama and Trump administrations appear to have assumed authority from the 1973 War Powers Act; there was no other authorization from Congress that I have been able to find.

Even assuming the U.S. is only giving the Saudis et al. arms and intelligence: In January 1941, President Franklin Roosevelt asked Congress for permission to give military aid to Britain by introducing the Lend-Lease Act. The lend-lease program gave FDR the power to lend arms to Britain with the understanding that eventually the U.S. would be paid back. The program could be extended to any country whose defense was vital to the security of the United States. Congress passed the bill by a large majority. But now, presidents are just making these decisions by themselves.

But getting back to Trump’s veto — it seems to me that even if there wasn’t a veto-proof vote, something like this shouldn’t be something he can veto. War powers belong to Congress. Congress gave the President a directive. Why isn’t he simply compelled to obey it? But no one seems to be saying that the veto can be challenged in court.

So that’s how the system works. It stinks, but as Uncle Walter used to say, that’s the way it is.