The United States is not a monarchy, but in times of nuclear crisis it sure feels like one. In his capacity as commander in chief, the president of the United States has sole authority over whether to launch a nuclear strike. He does not need to consult his military advisers, he does not need approval from Congress, it is his call alone.  That is a risky protocol under any circumstances, but when the Oval Office is occupied by someone with the temperament of Donald Trump, it should trouble Americans of all political persuasions. This is especially true when the United States confronts an adversary whose own leader, North Korea’s Kim Jong-un, seems to be itching for a fight.

The Korean conflict is escalating by the day as the two men’s macho posturing intensifies; we are fast approaching a situation like the Cuban missile crisis of 1962, when the US and Soviet Union came perilously close to blowing each other to bits. It is imperative to immediately ratchet down tensions between the US and North Korea and above all to make sure no nuclear weapons are fired. Even a single nuclear blast would unleash “inconceivable death and destruction,” James Clapper, the former director of National Intelligence, told CNN last night.

To lessen the chances of catastrophe on the US side, senior leaders in Congress from both parties should immediately communicate to the White House that the president must not launch a nuclear first strike without obtaining a congressional declaration of war. Congressional leaders should also urge the president’s top military advisers—the secretary of defense, the chairman of the Joints Chiefs of Staff, and the national security adviser—to take all measures available to assure that the president does not launch a nuclear attack without the advisers’ express agreement that such an attack is unavoidable to protect the American homeland. Meanwhile, efforts to engage in diplomatic dialogue with North Korea—aided by its sponsor state and neighbor, China, which doesn’t want nuclear war either—must redouble.

Whoever might start it, everyone loses in a nuclear war. It is by no means clear that Donald Trump understands this core truth of the nuclear era. Until he does, we need to get his finger off the nuclear button, or at least broaden the circle of officials with the authority to make that awesome decision. We need to demand dialogue rather than escalation. Public servants with inside influence should be sending this message loudly and clearly to the White House, and so should ordinary citizens. Now is the time for marches in the streets urging no nuclear war, and especially no first strike.

Leave politics and ideology aside for the moment; this is not a partisan plea. It is not a call to lower America’s guard against potential nuclear attack by North Korea, which is an undeniably dangerous and nasty regime. But North Korea now has the capacity to strike the US mainland with a nuclear weapon, according to the Pentagon’s Defense Intelligence Agency and independent analysts, and that changes everything. The United States must proceed with steadiness and resolve but also reason and prudence. Alas, the current commander in chief demonstrates none of these qualities. Common sense dictates that a president with Donald Trump’s volatile temperament and erratic judgment should not be empowered to single-handedly start a nuclear war.

At present, US law and long-standing policy give president Trump unilateral, unstoppable authority to launch a nuclear attack. He need not present a compelling reason for such an attack; perhaps he simply decides that it’s time to teach North Korea a lesson. He need not notify, much less obtain agreement from, leaders in Congress or the secretary of defense or other military officials. Trump’s status as commander in chief empowers him and him alone to unleash nuclear weapons at a moment’s notice.

“Seven hundred strategic warheads in silos and submarines are poised for immediate launch, and the president has absolute, unchecked authority to order their launch with a single verbal command to the Pentagon War Room,” Bruce Blair, a former nuclear-launch officer for the US Air Force and current scholar with Princeton University’s Woodrow Wilson School of Public and International Affairs, told The Nation. Trump need only turn to the military officer who carries the nuclear-codes suitcase, who is never more than a few feet away. The officer opens the suitcase (the so-called “football”), Trump makes one phone call authenticating his identity, and he orders the warheads unleashed—warheads that, once launched, cannot be called back.

“Four minutes after he gave the order, missiles would fly; 30 minutes later, they would explode on their targets,” explained Joe Cirincione, a former staff member of the US House of Representatives Committee on Armed Services and current president of the Ploughshares Fund. “Hundreds of targets. As quickly as he could post a tweet, Trump could destroy human civilization.”

All US presidents of the nuclear age have possessed the same awesome, unfettered authority Trump currently holds. But none of those presidents, with the possible exception of Richard Nixon during the darkest days of Watergate, displayed the psychological profile of the current commander in chief. Donald Trump “has shown himself time and again to be easily baited and quick to lash out, dismissive of expert consultation and ill-informed of even basic military and international affairs—including, most especially, nuclear weapons,” stated a public letter Blair and nine other former US nuclear launch officers released a month before the 2016 presidential election.

Could the military veto an ill-advised attack order from Trump? There is precedent: When Nixon was brooding and drinking heavily in the final months of his presidency, Defense Secretary James Schlesinger reportedly instructed the Joint Chiefs of Staff that “any emergency order coming from the president” should first be cleared with Schlesinger or the secretary of state, Henry Kissinger. Have Trump’s secretary of defense or the chairman of the Joint Chiefs of Staff implemented any similar measures? The Pentagon press office declined to comment.

Defense Secretary Mattis and Joint Chiefs of Staff chairman Dunford “are sober, prudent, and intelligent individuals who must be concerned about Trump’s impulsiveness and have surely considered how to ensure that he does not make a bad nuclear call,” said Blair. “They may well have taken extraordinary steps to ensure that a presidential command to use nuclear weapons would require their approval under unusual circumstances—e.g., out of the blue the president orders a preventive nuclear strike against [North Korea].” Steven Pifer, an arms-control expert at the Brookings Institution, also praised Mattis and Dunford as “sober-minded individuals” who “might try to intercede if they saw an inappropriate order.” However, Pifer stressed, “the system is not designed to give others a veto over a presidential decision.”

The system, then, must be changed. Set aside political ideology and partisan calculations for the moment. For the sake of the nation and indeed humanity, it is imperative to reform US nuclear-weapons policy. Start with three concrete, common-sense measures: The United States should take its nuclear weapons off of “hair-trigger” status; it should declare a policy of “no first use” of nuclear weapons; and it should prohibit this or any president from unilaterally launching a nuclear attack. Instead, it should require the president to act in concert with military and congressional leaders—except under exceptional circumstances, such as an adversary’s imminent nuclear attack.

Launching a nuclear attack is “a decision [so] momentous for all of civilization [that it] should have the kinds of checks and balances on executive powers called for by our Constitution,” said William Perry, the US defense secretary from 1994 to 1997. Perry has urged Congress to pass the Restricting First Use of Nuclear Weapons Act of 2017, introduced in January by Senator Edward Markey, a Democrat from Massachusetts, and Representative Ted Lieu, a Democrat from California. To bring Congress into the decision-making loop and prohibit the president from acting unilaterally, the bill stipulates that “the President may not use the Armed Forces of the United States to conduct a first-use nuclear strike unless such strike is conducted pursuant to a declaration of war by Congress that expressly authorizes such strike.”

“In addition to passing Markey-Lieu, the single most important other step would be to take our nuclear weapons off hair-trigger alert,” said Cirincione. “Currently, four minutes after Donald Trump gives an order, hundreds of nuclear warheads could be launched. Each is many times more powerful than the bombs that destroyed Hiroshima and Nagasaki. This is insane. There is no need for this rapid-launch capability. Having our missiles ready to launch in hours, days, or weeks instead of seconds would provide some time for reflection, debate, and possible reversal of a launch command. Secretary Mattis could do the nation a great service by recommending in his Nuclear Posture Review, due out late this year, that this Cold War practice be ended.”

None of these reforms will happen without strong, sustained public pressure. “Removing nuclear weapons from hair-trigger alert, adopting a no-first-use policy, and passing the Markey-Lieu legislation…will require grassroots energy and political will that, until Trump, has been dormant for decades,” Meredith Horowski, the global campaign director for the NGO Global Zero, told The Nation. “Now many Americans are waking up to the nuclear danger posed by Donald Trump,” she said. “That’s why in the coming weeks Global Zero and partners are mounting a new large-scale grassroots campaign—of students, activists, community leaders, universities, institutions, cities, and elected officials—to powerfully reject Donald Trump’s sole authority to launch us into nuclear war.” The campaign is slated to begin with a Day of Action in Washington, DC, on September 25.

There is no more urgent issue confronting the nation than Donald Trump and the nuclear button. Climate change, which likewise poses an existential threat to civilization, does not have such a short fuse. Fights over health care, immigration, budgets, and taxes—these can be won or lost today but resumed tomorrow. Go wrong with nuclear weapons, and there may be no tomorrow.

Editor’s Note: This article was updated in light of recent news events on August 9, 2017.