Wherever the President of the United States travels, a military aide-de-camp carrying “the football” is just a few steps away. It isn’t the kind Tom Brady throws. In the laconic jargon that national security officers use, “the football” is a briefcase that allows the President to launch a nuclear attack.

These days “the football” seems closer to being used than at any time in the last half-century. President Trump has issued thinly veiled threats of a nuclear first strike against North Korea. His emotional volatility makes those threats terrifying. Because of a deep flaw in our legal order, this is an existential fear rather than a theoretical one.

American law allows the President to launch a nuclear strike on the basis of nothing more than his own impulse. He need not provide any reason or consult anyone else. Vice President Dick Cheney seemed to salivate when he described the breadth of a president’s authority to incinerate nations.

“The president,” Cheney told an interviewer in 2008, “could launch a kind of devastating attack the world’s never seen. He doesn’t have to check with anybody. He doesn’t have to call the Congress. He doesn’t have to check with the courts. He has that authority because of the nature of the world we live in.”

Framers of our Constitution, acutely aware of how monarchs and tyrants had misused their authority, took great pains to limit presidential power. Thanks to their foresight, presidents may not declare war or levy taxes. They may name cabinet secretaries and ambassadors only with the consent of the Senate. The Supreme Court may reject laws they sign. Their freedom to act is remarkably limited.

The framers could not have imagined the apocalyptic power of nuclear weapons. Recent events make clear that this is the gaping hole in our system of checks and balances. President Trump cannot remove a local school board member, but if the impulse should strike him while he is relaxing at Mar-a-Lago, or if he is seized by anger when awoken and informed of some violent provocation in a distant land, he can call for “the football.” Nuclear weapons would be in the air within minutes.

“I could leave this room, and in 25 minutes, 70 million people would be dead,” President Richard Nixon told members of Congress in 1973. Was he considering it? Was he joking? Was he drunk? None of that matters. The key fact is that he was correct. Secretary of Defense James Schlesinger, according to later reports, became so concerned about Nixon’s mental health that he ordered officers in the nuclear chain of command to check with him before following any “unusual orders.” Trusting that today’s Pentagon is similarly engaged is a leap of faith.

The Nixon experience might have led Congress to impose some limit on the ability of presidents to set off nuclear war. It did not. Today the challenge is more urgent than ever. President Trump has asserted that he is prepared to set off horror “the likes of which the world has never seen before.” That should focus attention on the reality that under American law, this single individual has the right to launch a nuclear war.

It would be a horror without precedent. The atomic bomb attacks on Japan in 1945 were of an entirely different magnitude. Nuclear weapons of that era were primitive by modern standards. More important, Japan had no nuclear weapons with which to retaliate. Attacking North Korea would likely set off a holocaust.

President Harry Truman, who ordered the bombing of Japan, was not required to seek approval from anyone before doing so. Nonetheless he did. Truman wanted to assure himself that others with more experience and expertise shared his belief that a nuclear attack on Japan was justified. He secretly created what he called the Interim Committee — so named because it was established to make only a single recommendation — and asked for its opinion. Secretary of War Henry Stimson was the chairman. Its other members were the president of Harvard, the president of MIT, and senior representatives of military and security agencies. The Interim Committee reviewed intelligence and interviewed physicists who had developed the nuclear bomb, including Enrico Fermi and J. Robert Oppenheimer. After three weeks of deliberation, it advised Truman that it agreed with his decision to attack.

Some in Washington, shaken by President Trump’s rhetoric, are seeking to restrict his power to launch a unilateral nuclear attack. Nine members of the House of Representatives have filed a bill called the Restricting First Use of Nuclear Weapons Act. Its principle is not new, but in recent weeks it has taken on a new urgency. Under its provisions, presidents would be allowed to launch a nuclear first strike only after Congress has declared war and authorized such a strike. One of the co-sponsors, Rep. Earl Blumenauer of Oregon, asserted that since “Trump has already threatened nuclear war,” Congress needs “tools to prevent him from stumbling into the destruction and utter annihilation of millions of lives.”

Congress has not shown even the courage to limit a president’s power to wage conventional war. Determined to avoid responsibility for major national security decisions, it allowed wars in Vietnam, Iraq, and Afghanistan to rage for years without fulfilling its constitutional duty to declare or refuse to declare war. Congress is unlikely suddenly to grow a spine and assert its right to play a role in making what could be the most consequential war-or-peace decision in world history.

Questioning the president’s power to launch a nuclear first strike can be dangerous. During a training session in 1973 — when Nixon was at his most volatile — an officer posted at Vandenberg Air Force Base in California asked what may have seemed a reasonable question: “How can I know that an order I receive to launch my missiles came from a sane president?” The answer came quickly. The inquiring officer, Major Harold Hering, was discharged from the Air Force for “failure to demonstrate acceptable qualities of leadership.” He became a truck driver.

Can there be any restraint if presidents refuse to consult something like Truman’s Interim Committee, if Congress will not act, and if the military considers it taboo to question how it should respond to an order from a berserk president? During the 1980s Roger Fisher, a pre-eminent expert on conflict resolution, offered a provocative answer.

Questioning the president’s power to launch a nuclear first strike can be dangerous.

“Put that needed code number in a little capsule, and then implant that capsule right next to the heart of a volunteer,” Fisher suggested. “The volunteer would carry with him a big, heavy butcher knife as he accompanied the President. If ever the President wanted to fire nuclear weapons, the only way he could do so would be for him first, with his own hands, to kill one human being. . . He has to look at someone and realize what death is — what an innocent death is. Blood on the White House carpet. It’s reality brought home.”

More than 200 years ago, James Madison wrote that consolidating power in the hands of a single leader “may justly be pronounced the very definition of tyranny.” Thomas Jefferson asserted that the only way to avoid such tyranny was to elect a leader and then “bind him down from mischief by the chains of the Constitution.” They and the other Founders took pains to assure that no president would ever be able to order arbitrary arrests, unfair trials, or suppression of public liberty. If they could have imagined the power of nuclear weapons, they certainly would have taken a comparable precaution. Giving one individual the power to set off nuclear war would have been abhorrent to the framers of our Constitution. Limiting that power would honor their memory while increasing the odds for humanity’s survival.

Stephen Kinzer is a senior fellow at the Watson Institute for International and Public Affairs at Brown University.