Although it’s a bit more complicated, the short answer is No.
The President has complete authority to order such an attack at any time for any reason, and he requires approval from no one else.
James Clapper, the former Director of National Intelligence, said,
[If] in a fit of pique, [Trump] decides to do something about Kim Jong-un, there’s actually very little to stop him. The whole system is built to ensure rapid response if necessary. So there’s very little in the way of controls over exercising a nuclear option, which is pretty damn scary.How did that happen?
The presidential power to unilaterally “push the button” became policy in the 1950s during the Eisenhower Administration, shortly after the Soviet Union developed nuclear capacity. The purpose of this authority was actually to decrease the likelihood of nuclear confrontation by preventing field commanders from “freelancing” with nuclear weapons.
Policy makers at the time, however, believed that the possibility of an imminent or actual nuclear attack required the capacity to respond immediately, perhaps within minutes. In such a case there would be no time for two or more people to come to agreement. Accordingly, they vested the President with absolute authority to launch. In addition, this capacity for immediate response was a necessary element of the “mutually-assured-destruction” policy that was the cornerstone of nuclear strategy during the Cold War.
Policy makers, of course, can be forgiven for their expectation that any future President would be informed, competent and have their impulses under control and—except in the case of imminent or actual attack—would consult with their cabinet and military before launching nuclear weapons.
It turns out, however, that there is no “nuclear button.”
The “Nuclear Button” is really a highly complex system of communication and codes, established to insure that any order to launch a nuclear attack is actually coming from the President, and hasn’t been schemed or invented by someone else.(You can find an excellent description of that system here.)
Once the President has ordered the attack, there is no legal way to countermand the order. The process does have to go through the Secretary of Defense. By law, however, the only role for the Secretary is to determine that the order actually comes from the President. The Secretary has no authority to evaluate the appropriateness of the order, only to execute it by passing the order to the military combatant commander, who then sets the attack into action.
What if the Secretary decided not to follow the President’s command? His only option would be to resign or be fired. The Secretary of Defense—like all other cabinet officers—serves at the pleasure of the President who can fire them immediately and appoint someone who will follow the order.
Richard Nixon’s "Saturday Night Massacre" is the most famous example of a President firing a recalcitrant cabinet member. After receiving Nixon’s order to fire the independent special prosecutor investigating the Watergate scandal, Attorney General Elliot Richardson refused, so Nixon fired him. At that point, Deputy Attorney General William Ruckelshaus automatically became acting Attorney General, but he also refused Nixon’s order. It was only after US Solicitor General Robert Bork, the-next in line to become acting head of the Justice Department, complied with Nixon’s order that it was carried out.
Similarly, the combatant commander could refuse to pass on the order, but he, too, would be by-passed (and then would be subject to military court martial and probable heavy punishment.)
The Secretary of Defense could, therefore, theoretically stall the process (perhaps by hours), hopefully giving presidential advisors time to convince the President to retract the order. But there is no legal means to stop the President from firing as many acting Secretaries of Defense as necessary to find one who will execute his order.
For practical purposes, then, the President can—completely on his own—order a nuclear strike, “which is pretty damn scary.”
ADDENDUM:
There was an editorial Nov 25 in the Washington Post that suggested that there are more constraints
on the President's use of nuclear weapons than I suggested above. The editorial is well worth
reading. The main details that I did not have in my original post are:
1. In the previous post I said that the
President needed complete authority to press the nuclear button because he
would need to be able to respond within minutes to any threat. The Post editorial pointed out unlike the
Cold War when the Soviet Union and the United States could hit each other
within thirty minutes, and a "hair-trigger" alert seemed necessary. North Korea would not be tempted to a “sneak
attack” on the US because it wouldn’t be able to destroy all our launch sites ,
for, unlike the Soviet Union, they could not destroy our retaliatory capacity In
the unlikely event that North Korea did launch a nuclear weapon toward us
(which we wouldn't be able to stop, anyway), we would lose at most one city
while North Korea would undoubtedly be obliterated in response. The Cold
War scenario gave the President no time to consult with anyone, so the
circumstances called for absolute authority seemed necessary. The current
situation with North Korea gives us plenty of time for a reasoned response. So, it seems to me, it would be reasonable
for Congress to legislate a mandatory consultation before ordering the
strike. But there is no such law today.
2. Under international and
domestic law any weapons use “must comply” with requirements of the Law of
Armed Conflict: “military necessity, avoidance of unnecessary suffering,
proportionality and discrimination or distinction.” A nuclear first-strike
would be against that law. Furthermore, recently retired US general
Robert Kehler, until 2013 head of the US Strategic Command testified to
Congress if the commanding general determines the order is illegal they can and
should countermand the order. But, as I
pointed out in my original post, the President could just fire one general
after another until he found one willing to carry out his order.
