President Donald Trump and Mr Kim Jong Un are engaged in an increasingly dangerous showdown. New rules are needed to prevent us from stumbling into nuclear war.
For the first time in a generation, there is widespread anxiety about the possibility of nuclear war, stimulated by the extreme tensions between North Korea and the United States. Secretary of State Rex Tillerson has advised Americans that they can sleep safely at night, a reassurance that most people probably wish they did not need to hear.
Mr Tillerson offered his soothing counsel to deflate media hype about recent threats and counter-threats exchanged between Pyongyang and Washington. His words also reflect profound unease about the temperament and judgment of the two leaders who could trigger inadvertent war: President Trump and Mr Kim.
Mr Trump and Mr Kim appear to believe that bombast serves their domestic needs. Both seem to think that they can dominate and intimidate through the direst of threats. However, words can easily have consequences that neither leader seems to grasp.
Should we be living in a world where two leaders can stumble into a nuclear holocaust?
North Korea's accelerated pursuit of nuclear weapons clearly requires a much-enhanced containment and deterrence policy by the US and its allies to prevent Mr Kim from undertaking ever-riskier options. But what can be done to constrain the actions of an American president whose stability is now openly questioned, even by the Republican chairman of the Senate Foreign Relations Committee, Mr Bob Corker of Tennessee?
To limit the possibilities of an almost unimaginable conflict, there is a need to pursue a long-overdue legislative remedy.
Under Article I of the Constitution, only Congress can declare war.
Yet during America's numerous wars since World War II, presidents have never sought such authorisation.
The major reason? Nuclear weapons. There was widespread agreement that the president needed maximum flexibility to respond to a Soviet attack and that involving Congress would cause undue delays in a moment of crisis. As a result, the president has had essentially unchecked power to wage war, including launching a nuclear strike.
However, strategic planners understood the risks of enabling a single officer in a silo in North Dakota, perhaps under the most stressful conditions imaginable, to initiate a nuclear strike. The nuclear command-and-control system therefore entailed a "two key" system requiring simultaneous actions by two officers to activate a launch.
The time is long overdue to introduce comparable checks at the highest levels of the executive branch.
The strategic circumstances faced by the US today are altogether different from those during the Cold War. Despite heightened tensions triggered by Russian revanchism in Ukraine and elsewhere in Central and Eastern Europe, the real risk of nuclear war emanates from a rogue actor, and North Korea heads the list. Almost-casual presidential invocations of fire and fury have rendered circumstances far more dangerous.
The US should in no way diminish its ability to respond to a nuclear or conventional attack by North Korea against US territory or the territory of an ally. However, we should put in place a system of constraints to ensure that a preventive or pre-emptive nuclear strike by the US must be evaluated through a careful, deliberative process. Congress should therefore amend the War Powers Act to cover the possibility of preventive or pre-emptive nuclear strikes. This would ensure that the president could not simply provide the codes to his military aide carrying the nuclear "football" and launch such an attack on his own authority.
Legislation should provide for a small group of officials, possibly including the vice-president, the secretary of defence, the chairman of the Joint Chiefs of Staff and the four leaders of the House and Senate, to give unanimous consent to any such nuclear strike. It would ensure that multiple sets of eyes, equipped with stable emotions and sound brains, would be able to prevent such a nuclear strike undertaken without appropriate deliberation.
This proposal would raise difficult constitutional questions. All presidential administrations have deemed the War Powers Act to be unconstitutional. Giving officers appointed by the president and subject to his direction formal veto power over military decisions could be problematic and precedent setting. If so, confining the veto power to the congressional leadership might be a preferable alternative.
Even during the Cold War, there was great risk in ceding to one person the ability to kill millions in a flash. There is no good reason to enable an American president to retain absolute authority in circumstances completely unlike those faced during the Cold War.
Assurances that nuclear weapons remain an option of absolute last resort, to be considered only after the concurrence of leaders from the executive branch and from Congress, would also calm the nerves of US allies deeply troubled by loose talk about the resort to nuclear weapons.
This is not to suggest that President Trump nurses some secret desire to launch a nuclear attack. However, the US needs to act very prudently in dealing with an isolated and uniquely adversarial state.
For its part, Congress has the power to prevent hair-trigger responses or impulsive actions that could lead to nuclear war.
• Jeffrey Bader was a senior adviser to President Barack Obama on Asia from 2009 to 2011. Jonathan D. Pollack is a senior fellow at the Brookings Institution, specialising in Korea and China, and was a professor at the United States Naval War College.