Can the U.S. president make military decisions without consulting anyone?

Question

Looking on Wikipedia, we learn that:

It is generally agreed that the commander-in-chief role gives the President power to repel attacks against the United States[3][4] and makes the President responsible for leading the armed forces. The President has the right to sign or veto congressional acts, such as a declaration of war, and Congress may override any such presidential veto. Additionally, when the president's actions (or inactions) provide "Aid and Comfort" to enemies or levy war against the United States, then Congress has the power to impeach and remove (convict) the president for treason. For actions short of treason, they can remove the president for "Bribery, or other high Crimes and Misdemeanors", the definition of which the Supreme Court has left up to Congress. Therefore, the war power was intentionally split between Congress and the Executive to prevent unilateral executive action that is contrary to the wishes of Congress.

But the question is if the President can make direct orders without consulting any of his general through a phone call. For example, can the President order the U.S. military to launch a bomb against Canada without any reason? It is not explicitly stated if he can do so, but it seems that he can, but risk being impeached for such random and foolish decisions.

Answer 1

Yes and no.

The War Powers Resolution (sometimes known as the War Powers Act) is supposed to limit it.

The War Powers Resolution requires the President to notify Congress within 48 hours of committing armed forces to military action and forbids armed forces from remaining for more than 60 days, with a further 30-day withdrawal period, without a Congressional authorization for use of military force (AUMF) or a declaration of war by the United States. The resolution was passed by two-thirds of each of the House and Senate, overriding the veto of the bill from President Nixon.

In theory, it limits the unilateral war actions of the President beyond 60 days. In practice, it has not really changed anything. Every President has violated the WPA since its passage, with all of them (both parties) believing it too be unconstitutional. Even Obama, who endlessly praised it

President Obama, in defending the legitimacy of the Libyan operation, hasn’t actually made that argument. On Wednesday, he submitted a report to Congress arguing that his administration isn’t in violation of the act at all, despite the fact that the 60-day deadline for congressional approval of Libya operations came and went in May.

President Obama is far from alone in finding creative ways around the War Powers Act. As the New York Times has noted, the Clinton administration continued the bombing campaign in Kosovo past the 60-day deadline, arguing that Congress had implicitly approved the mission when it approved funding for it. (The Act specifically says that funding doesn’t constitute authorization, the Times notes. And Obama wouldn’t be able to use that reasoning anyway—the administration is using existing funds for the Libya mission.)

Does that mean the President is not constrained by Congress at all? Hardly. As the House notes, they still hold the power of the purse

Congress—and in particular, the House of Representatives—is invested with the “power of the purse,” the ability to tax and spend public money for the national government.

Let's say a President tried to start a war without Congress. They would quickly find out the military did not have funding to run the war for very long. As a result, the military would be hamstrung in operating without funds. It would not bode well for anyone to be squabbling politically while troops were deployed to a military theater, but at that point, the war would become a direct political question. If people felt the war should not be pursued, they could elect people who would refuse to fund it. If people felt the President was right, they could vote people in who would fund it.

Let's finish this by talking about this hypothetical bombing of Canada. Without a good reason, the President would quickly find themselves on the losing end of public opinion (neither party would tolerate a direct act of aggression), and possibly facing impeachment.

Answer 2

2017 Shayrat missile strike

On the morning of 7 April 2017, the United States launched 59 Tomahawk cruise missiles from the Mediterranean Sea into Syria, aimed at Shayrat Airbase controlled by the Syrian government. The strike was executed under responsibility of U.S. President Donald Trump, as a direct response to the Khan Shaykhun chemical attack that occurred on 4 April.

The strike was the first unilateral military action by the United States targeting Ba'athist Syrian government forces during the Syrian Civil War. Trump stated shortly thereafter, "It is in this vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons."

So if you can 'prove' (or get enough people to believe) that maple syrup is a threat to national security, then you can bomb Canada without repercussion. Or you could just do it anyway:

The strike was conducted without either U.S. congressional or United Nations Security Council approval.[23][24][25][23][26][27][28]

That's at least one instance of "unilateral executive action" and it was "contrary to the wishes of [at least one member of] Congress" :

Representative Adam Schiff (D–CA), the Ranking Member of the House Intelligence Committee, was informed of the strike by Dan Coats, the Director of National Intelligence, as it was happening. He urged the administration "not to make this a military effort to change the regime".

Answer 3

US soldiers swear to follow orders which are legal according to the Uniform Code of Military Justice, and are explicitly disallowed from following orders which are unlawful. Any Presidential power to use troops has to come from an Act of Congress per Article 1, Section 8, Clause 11 of the US Constitution

[The Congress shall have the Power] To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water

Congress has already granted the President broad power to use troops offensively without prior consent through the War Powers Resolution, but has also ratified membership in the NATO, which Canada is also a member of and almost certainly includes a provision against members attacking each other. Ratified treaties have equivalent power to an Act of Congress, so an officer would probably be justified in refusing to follow an order to attack Canada unprovoked without Congressional approval.

The Constitutionality of the War Powers Resolution is disputed by scholars, especially the effective blanket approval for military action without specific authorization from Congress. However, President is not legally required to consult with anyone prior to ordering a military action in general, and the legality of such an action would be determined after it was ordered - put differently, the President doesn't have to prove an order is legal before giving it, it's up to the military to refuse to follow it if it is unlawful.

Answer 4

Frame Challenge

the question is if the President can make direct orders without consulting any of his general[sic] through a phone call.

This question means that he's skipping many layers of the chain of command (Joint Chiefs of Staff, Commands, Divisions/Wings/etc), jumping straight down to a Colonel and telling him Attack Canada!, ignoring all the logistics of how that Colonel transports his Brigade Combat Team from whatever base it's at to Canada.

(Sure they've got some organic transportation, but eventually they run out of fuel and food, and the Colonel can't just contact the Transportation Corps and Quartermaster Corps and say, "send me fuel and food because POTUS ordered me to attack Canada!")

And who exactly would he give the order to?

Answer 5

You ask

Can the U.S. president make military decisions without consulting anyone?

Can he? Yes, he can. (That much is trivial.)

Would it be legal? According to the constitution, it seems like it, at least in an emergency: "the Justice Department’s Office of Legal Counsel has claimed that the Constitution authorizes the president, as commander in chief, to order the military to attack other countries without congressional permission" (https://www.nytimes.com/interactive/2019/us/politics/presidential-war-powers-executive-power.html). So the civil checks are off, in the opinion of the OLC which is, one could say, the authority on that matter, biased as it may seem on occasion. As far as the military side is concerned, he is commander in chief, which kindof settles the matter, if I understand correctly the prime directive of the military: Follow orders.

This covers national law; the international law is less clear, but of course there have been convictions for crimes against humanity or war crimes. In most cases such trials (which will determine legality or illegality) are only possible against governments of defeated nations or ousted leaders, which makes the probability of such a determination for actions of an American president unlikely, unless Congress brings itself to impeach. Conceded, nuking another nation for no good reason would likely raise the chances of an impeachment.

Would the president's solitary military decisions be executed? Now here is an interesting question, which was discussed in another New York Times article. It appears that while the military chain of command is clearly defined, orders can be executed with different levels of expedition and eagerness. Not every command from the top may be executed without delay and detour. This is more likely when the president is under unrelated stress or his judgement appears otherwise impaired. To quote another New York Times article:

In real life, the lines of authority have blurred — markedly so during the Nixon administration, when there were at least two instances in which top officials tried to slow, or undermine, the president’s nuclear authority.

President Trump's judgement was questioned from a different angle — there was some debate about his sanity when he entered office. Apparently it was just above a level that would have warranted removing him from office for medical reasons.

An anonymous opinion piece from a White House senior official in the New York Times stated:

Some of his aides [...] have gone to great lengths to keep bad decisions contained to the West Wing, though they are clearly not always successful. [...] It may be cold comfort in this chaotic era, but Americans should know that there are adults in the room. We fully recognize what is happening. And we are trying to do what’s right even when Donald Trump won’t.

The other article concluded:

“In some scenarios,” Mr. Sagan [a nuclear expert at Stanford University] added, “such as an unprovoked nuclear attack by a president in peacetime, a constitutional crisis would be more likely than a prompt following of rules regarding succession and command authority.”