The simmer of unease prompted by the prospect of Donald Trump in command of nuclear weapons—initially highlighted during last year’s presidential campaign—reached full boil last week. A Senate Foreign Relations Committee hearing on nuclear use authority included clear expressions of concern, most pointedly from Sen. Chris Murphy, a Connecticut Democrat who said he and others were concerned “that the president of the United States is so unstable, is so volatile, has a decision-making process that is so quixotic, that he might order a nuclear weapons strike that is wildly out of step with US national security interests.” But the Senate hearing resulted in no immediate consensus on the ways in which a president’s relatively unfettered authority to launch nuclear weapons might be modified without raising significant constitutional questions.

Indeed, the hearing and a wide range of commentary that followed illustrate the tension that exists between a president’s constitutional position as commander in chief, obligated to protect the United States from foreign threats, and the constitution’s delegation to Congress of the power to declare war. Under the current system, a president is the only US official who can order a nuclear attack. To be sure, such a decision is unlikely to be made without significant input from his national security advisers. Military commanders could theoretically refuse to execute an “illegal” nuclear-strike order, but such orders are presumed legal. A president is certainly allowed to consult with Congress ahead of a nuclear attack or response. But given the extremely tight time constraints under which a decision to use nuclear weapons might be made, consultation is not necessarily contemplated under the current nuclear command and control system, and the sole authority for deciding to use nuclear weapons belongs to the president.

Perhaps the most nuanced of the commentaries to follow the Senate hearing came from one of its witnesses, Duke political science professor Peter Feaver. As both his testimony and a subsequent article in Foreign Policy magazine attest, the precise chain of command that would result in use of the US nuclear arsenal is not a simple thing to explain in public, in part because many of its particulars are classified. Feaver’s bottom line: A congressional review of nuclear command-and-control issues is warranted, given that no such formal review has occurred for decades, but Congress should avoid hasty legislation that could have unintended and highly dangerous consequences, perhaps leading adversaries and allies to question the United States’ ability to respond quickly in a crisis situation.

“[W]e should be wary about second- and third-order consequences and so should scrutinize proposals [to change nuclear command authority] with as jaundiced an eye as we scrutinize claims by nuclear operators that suggest ‘all is well, nothing to see here…’” Feaver wrote.

Feaver’s discussion of the always/never dimension of US nuclear command and control—the system should always respond with a nuclear strike when required, yet never allow an accidental or unauthorized use of nuclear weapons—is particularly worth reading. And his explanation of the conceptual differences between two general nuclear-use situations—one in which the military “wakes up” the president and asks him to respond to an imminent or actual nuclear attack, and another in which the president “wakes up” the military with an order to use nuclear weapons first—illuminates the real-world complexity of nuclear decision making. All nuclear situations are not made equal.

In an appearance on CSPAN, Stevens Institute of Technology nuclear historian Alex Wellerstein explained the general outlines of the US nuclear command structure in a perhaps more accessible way. His answer to the question of whether Congress could or should place limits on a president’s ability to order a nuclear strike is worth quoting in its entirety:

I think Congress should at the very least have some very frank discussions about whether or not the current system is the best of all possible worlds, whether or not the current system is as safe as it could be with regards to the fact that any president—and it doesn’t have to be Trump, [though] Trump has obviously raised a lot of these concerns—but any president is a single human being. We have plenty of examples of presidents who were fallible, president who suffered from mental illness, presidents who were addicted to various types of substances. If you go through American history, it’s very hard to come away with the idea that presidents are somehow above it all. Could Congress do it? [That] gets into pretty thorny constitutional law questions. I don’t feel like we know exactly what the dimensions, the answer to that is. Congress has intervened with the War Powers Act in their role as a body that is meant under the Constitution to declare war. The president is the commander in chief. These things are somewhat at odds in our modern age, where the ability to use military forces and the ability to declare war can be nearly instantaneous, as opposed to say in the 18th century when the Constitution was drafted. Could they [members of Congress] do it? Maybe. Should they do it? I think they should look into it.

London Review of Books contributing editor Adam Shatz offers a sharper-edged take in a lengthy piece that focuses largely on the overwhelming concentration of power that the US presidency has acquired in recent decades.

“Perhaps the question we should be asking,” Shatz writes, “is not whether Trump can be stopped, but whether the system as a whole can be overhauled. ‘We have elevated the president to the position of a demigod, and then when he turns out to be Donald Trump, we’re shocked,’ [retired US Army career officer Andrew] Bacevich said to me. ‘But since Roosevelt we have vastly enhanced the power and prerogatives exercised by the president, and his ability to execute the nuclear war plan is just part of the package. Why have we entrusted this one imperfect individual with the power to blow up the planet?’”

In recent months, a bill proposed by Sen. Ed Markey of Massachusetts and Rep. Ted Lieu of California—the Restricting First Use of Nuclear Weapons Act of 2017—has gained much notice and significant support from experts and activists concerned by President Trump’s statements on matters nuclear, especially as regards his threat in August to inflict “fire and fury” on North Korea. The bill would prohibit the president “from using the Armed Forces to conduct a first-use nuclear strike unless such strike is conducted pursuant to a congressional declaration of war expressly authorizing such strike. ‘First-use nuclear strike’ means a nuclear weapons attack against an enemy that is conducted without the President determining that the enemy has first launched a nuclear strike against the United States or a US ally.”

In an interesting and perhaps surprising turn, the editorial board of the Los Angeles Times, which is essentially Lieu’s hometown newspaper and tends generally in a liberal direction, came out on Sunday against the Lieu-Markey bill, saying,

“Our principal concern about this bill is that it would make it harder for a president not just to use nuclear weapons, but also to deter aggression by leaving adversaries in doubt about whether and when such weapons might be used.”

This position points up the dilemma: Unfettered, an unhinged president could order an unwarranted nuclear strike that leads to global catastrophe. Controls on the president’s ability to order such a strike, however, could slow critical responses to aggression or embolden enemies.

The current US system of command and control gives the president such complete authority over whether a nuclear attack is ordered that Harvard University’s Elaine Scarry calls that system (in her book of the same name) Thermonuclear Monarchy. But there are other, less-monarchical systems, and the Union of Concerned Scientists has published an admirable roundup of open source information about how other countries with nuclear weapons control their use.

“Instead of relying solely on the judgment of a single individual to make a decision that could lead to worldwide devastation, most nuclear-armed states have put in place systems that—at least in theory—limit the ability of any one individual to independently order a launch,” the UCS report notes.

One can hope that members of Congress from both parties read the report and think long and hard about whether it is reasonable to place the fate of the entire world in the hands of one person. Any person.