It’s the totally unthinkable question that Americans find themselves confronting this week: What would President Donald Trump do in a genuine national crisis?

After a series of overseas terror attacks and some startling statements about nuclear weapons and torture, the world’s attention has turned to Trump’s foreign policy—an area where he has few advisers, no experience and a tendency to fire off answers and deal with the fallout later. The reality of a Trump candidacy has begun to set in: If Trump is elected and a major national crisis hits, he’ll be the one with his hands on the button. He’ll be at the head of the table in the Situation Room. His decisions would steer America’s immediate response and could set the course of American policy for years.


What’s hard to project with a normal politician is nearly impossible to guess with Trump. He has no foreign policy or public service experience, which means there’s no official record to consult, and his public statements, while extreme, have been vague. The saber-rattling statements that excite his supporters also suggest he has disregard for linchpins of the global order like NATO, the Geneva Conventions and the hard-won global nuclear-weapons limits.

Politico Magazine asked foreign policy and counterterrorism experts, historians, Trump biographers, even psychologists to take a serious guess at how he’d handle the days after a terrorist attack in the United States—all based on what they know about Trump the candidate and what he’ll be facing if he gets elected.

The responses were at times surprising, and at times unsettling. Some focused on Trump’s apparent hesitancy about sending troops into combat, and predicted he’d act more like President Barack Obama than President George W. Bush. Others looked at his immigration rhetoric and foresaw a country newly divided, with patrols stalking Muslim neighborhoods and religious hatreds bubbling to the surface. One biographer, familiar with Trump’s primal response to any perceived insult, drew a frightening picture of a quickly escalating set of attacks and responses, with major cities caught in the crossfire. But, then again, another predicted that Trump would simply withdraw to his Twitter account, riding out the threat with a lot of talk and little action.

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“He invites President Vladimir Putin to the White House … announces that America is withdrawing from NATO and … visits Tehran to open up a new American embassy.”

Jacob Heilbrunn is editor of the National Interest.

Donald Trump has already made it clear that he regards much of the global order that was established by Harry S. Truman and Dean Acheson after World War II as impotent and obsolete. Almost as soon as he’s sworn the oath to serve as commander-in-chief, Trump will go to work to create a new one based on the exercise of American military power and cooperation with Washington’s traditional adversaries such as Russia. So the real question may be this: How would a 9/11 event accelerate his already existing efforts to upend the American national security establishment?

Following the attack, President Trump builds upon his initial attempts to restore relations with Russia, which included nuclear arms-control negotiations. He now invites President Vladimir Putin to the White House—complete with a state dinner in his honor. Trump, the consummate dealmaker, says that it’s imperative to let bygones be bygones in the interest of a united front with Russia to defeat the Islamic peril. At the same time, Trump announces that America is withdrawing from NATO and concedes Russia’s sphere of influence in Eastern Europe. England, which has already withdrawn from the European Union, joins the U.S-Russia alliance. In following this course, Trump invokes World War II to declare that he’s simply following in Franklin Roosevelt’s footsteps.

All of this is music to the Kremlin’s ears, which has consistently bemoaned the fact that the Obama administration has spurned its offers of cooperation. British, Russian and American warplanes bomb targets in Syria and Iraq that served as staging grounds for the Islamic State’s assault on America. In addition, Trump pivots from America’s traditional alliance with Saudi Arabia to working with Iran; to general astonishment, he visits Tehran to open up a new American embassy. Trump says that the only predictable thing about his presidency is that he will always seek to be unpredictable.

Domestically, Trump takes a hard line, arguing that it’s time to take the handcuffs off the FBI and CIA. He embarks upon a program to place American Muslims in camps, a program overseen by the Justice Department as it was during the Roosevelt administration in World War II, when Japanese-Americans were interned. The Washington Post and New York Times editorial pages denounce Trump’s new policy, but it meets with general approbation among the American population, a number of Democratic Senators and Congressmen in swing states sign off on the measure, and the Supreme Court upholds it in an 8-1 decision. With his decisive moves, Trump enrages liberal and conservative elites but his approval ratings soar to over 80 percent in numerous polls. The era of Trump has begun.

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“Tweet after tweet congratulating himself on foreseeing the attack and ridiculing the terrorists’ masculinity, their intelligence, their family members, their ethnic identity and/or religion”

Gwenda Blair is author of The Trumps: Three Generations That Built an Empire.

Twitter would be Trump’s front-line counter-attack. Tweet after tweet congratulating himself on foreseeing the attack and ridiculing the terrorists’ masculinity, their intelligence, their family members, their ethnic identity and/or religion—along with any civil libertarian or moderate voices asking for caution, consultation with allies, or more operational and regional intelligence before initiating counter-offensives against targets either inside or outside the United States.

Next would be live streamed appearances on CNN, Fox, MSNBC, etc. in which Trump denounced the terrorists, their supporters, and any opposition to the use of any and all tactics against captured terrorist suspects.

Then he would change into Donald Trump Menswear 100% silk PJs with gold-embroidered POTUS seal on front pocket, stretch out on a super-luxury top-grain leather Trump Home Furnishings chaise, chow down on a prime-cut Trump steak, and turn on WWE.

In the event the attacks continued, he might be moved to more action. Potential steps might include curfews, quarantines and/or internment in certain communities, required loyalty oaths for government employees, teachers, uniformed services, etc., civil defense drills in schools, factories, offices, and other large installations such as airports, train stations, subway systems, and the adoption and frequent testing of alerts through texts and loudspeakers.

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“There would be no rallying around the idea of America and what it stands for because Americans will be fighting about just that”

Ian Bremmer is president of Eurasia Group and a global research professor at New York University.

It’s not an easy thing to say, but America was fortunate that 9/11 happened when it did. The United States was in great shape back then, as was its economy. There was no serious social discontent bubbling beneath the surface, and inequality was nowhere near the wedge issue it is today. Washington’s alliances around the world were strong back then, and China was still weak. Washington even had decent relations with Moscow—and they improved after the tragedy. So when 9/11 happened, the entire country—and the world—rallied around the president.

That’s a far cry from where the United States is today. And let’s be honest—Trump in the White House during a real national security crisis is as close to a near-dystopian America as can be imagined. If terrorists were to hit the United States, America’s political response would be closer to what France went through following its November attacks, with Trump playing the reactionary role called for France’s ex-President Nicolas Sarkozy. He’d push for overall surveillance and monitoring of Muslims in the United States. I’d imagine there would be house arrests and deportations for many. And while some Americans would cheer this knee-jerk response, most will be horrified to find themselves living in a country where nothing more than your religion makes you suspect. Europe will be horrified as well, and won’t be near the steadfast ally it was in 2001. There would be no rallying around the idea of America and what it stands for because Americans will be fighting about just that.

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“A president with that personality would experience a large terrorist event as an enormous narcissistic injury … and his rage would be white-hot”

Martha Stout is a psychologist and author of The Sociopath Next Door.

As a psychologist who has spent her career studying human personality and its variations, I can tell you that personalities don’t have an off switch, not even for dire emergencies. If we suffered another brutal terrorist attack, I fear that President Trump would exhibit the same bombast, rage and impulsivity that he has shown in the campaign trail and imperil his fellow human beings, perhaps with even more lasting effects than those of the disaster itself.

The personality that underlies Trump’s observable behaviors—a demeanor of personal superiority, a focus on being admired, immediate heated anger when challenged, an emphasis on unlimited success, and an apparent expectation of automatic compliance—would be problematic in a U.S. president at any time, and plainly dangerous should our nation experience another terrorist atrocity. A president with such a personality would experience a large terrorist event as an attack on him personally, an enormous “narcissistic injury”—what psychologists call a perceived threat to self-worth—and his rage would be white-hot. The anger we have seen directed at protesters during Trump rallies would be multiplied by an unknowable factor. That whisper in the ear from an aide, telling him that an event had occurred, would instantly evoke a need for reprisal, a desire to attack and to do so right away, using airstrikes, boots on the ground, torture in interrogations and any other “powerful” tactic that occurred to him.

If there is a positive thread in this psychologically predicted scenario, it is that such a huge perceived injury to Trump’s sense of self-worth would compel him to focus utterly on the source of that injury. He would be single-mindedly intent on destroying the terrorists and would have no tolerance for those who might wish to refashion the country’s pain and anger into a willingness to attack a different target. In the aftermath of our waking nightmare in 2001, we might have benefited from some portion of that single-mindedness. Still, with a President Trump, the surge of bigotry and the resulting deportation and internment efforts would do their own inestimable damage.

Given a re-terrorized nation, Trump’s famous skill at gaining allegiance from people through their heightened fears might very well sway Congress and result in the actual implementation of some of his ideas: a wholesale military response, a lockdown of Muslim communities, and attempts to deport large groups of people. With an unapologetically self-involved and rage-prone commander-in-chief—which is what we evidently would be getting with a President Trump—nothing would be off the table.

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“We must also hope that a President Trump, unlike candidate Trump, would show some signs of awareness of the nature of the threat”

Ambassador Dennis Ross is a long-time U.S. Mideast negotiator and author of the recently published Doomed to Succeed: The US-Israeli relationship from Truman to Obama.

If such an attack takes place, it would be clear that Trump’s ill-considered readiness to stop Muslims from gaining entry to the country has not worked—no surprise here, as he is playing to the ISIS playbook that seeks polarization and needs the image of a war on Muslims to attract followers. The fact that Trump has little use for our alliances like NATO also means in the first instance, his response would likely be to go it alone. But against whom? Did the attackers come from ISIS and had they gone to Syria? Was al Qaeda competing with ISIS to show it remains relevant and capable of producing larger mass casualty acts of terror than ISIS?

Should it be ISIS, we know from candidate Trump that when it comes to ISIS he will listen to the military. But the military has not been notably more inclined than President Obama to commit forces on the ground. However, should ISIS prove to be responsible for a 9/11 type attack—and clearly the events in Brussels show its leaders are trying—we will need a far more dramatic effort against them on the group to demonstrate they are losing, and will lose further from any such attacks. Perhaps Trump, who has made it clear he is reluctant to use ground forces, will call for carpet-bombing as a punishment for ISIS. That will shift the onus onto us without removing ISIS from Mosul or Raqqa—the key symbols of their success to date. In the aftermath of a 9/11 type attack we need to inflict real and symbolic setbacks on ISIS to blunt its appeal and to restore confidence among our own citizenry and that of those very Sunnis we would want to partner with us. Are they likely to partner with us if we can’t offer unmistakable signs of success and of our resolve? They won’t take a new president’s word for it—or buy his “believe me” declarations. Will Trump change and see the value of working with others? Let’s hope so, but there is little in his posture to date that suggests he will do so.

We must also hope that a President Trump, unlike candidate Trump, would show some signs of awareness of the nature of the threat. Show some signs of awareness that actually having alliances like NATO helps with partners, helps with intelligence, and helps legitimize our actions. A President Trump will need to frame the challenge clearly and spell out the mission and objective in a way that does not walk away from the values that we embody. And a President Trump would have to show he will act not impulsively but effectively, recognizing that a longer-term strategy for the Middle East will be necessary, a strategy that is designed to shore up the state system. That system is under attack and restoring it is necessary to prevent ISIS or its successors from having the operational space in which to thrive and develop. Withdrawing from the Middle East will only foster a vacuum that allows the most extreme forces to emerge and pose more threat to states in the region. Candidate Trump’s instinct toward isolation can hardly be reassuring in this regard.

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“Let us imagine that when the new president enters the Situation Room to talk over the latest disaster, he’s got Steve Hadley and Eric Edelman and Meghan O’Sullivan around the table”

Stephen Sestanovich is a professor at Columbia University and a senior fellow at the Council on Foreign Relations.

In the national-security business, we are often asked to think the unthinkable—nuclear war, chaos, pestilence. Contemplating a Donald Trump presidency should be all in a day’s work. Even so, I find myself wanting to dodge the worst-case scenario. Perhaps this unlikely chief executive will prepare for his day of reckoning by surrounding himself with solid advisers and by tending, however belatedly, to America’s most important global relationships?

It’s not absurd to hope that long before taking office President Trump will have reached out to the Republican foreign-policy establishment and that, by playing on personal ambition and patriotism, he will have convinced those who hoped to work for President Rubio or President Jeb Bush to serve him instead. Nor is it absurd to think that, before a new 9/11, he will have realized that the United States cannot get much done in the world unless key allies are with us.

So let us imagine that when the new president enters the Situation Room to talk over the latest disaster, he’s got Steve Hadley and Eric Edelman and Meghan O’Sullivan around the table. (And maybe vice president Condi Rice ready to fly off to Brussels to represent him at the next day’s emergency session of NATO.)

Like I say, none of this is absurd. But I don’t expect it. Whatever you think of the results, the Republican Party’s A-team was across the table from George W. Bush on September 11, 2001. On September 11, 2017, by contrast, we are likely to have a foreign-policy line-up that reflects the party’s nervous breakdown in the 2016 campaign. The administration will be thinly staffed and often inexperienced, divided against itself, suspicious of the professional bureaucracy, struggling to develop coherent policies, and never sure what the president wants.

Donald Trump’s own ideas and instincts have to be part of the picture we draw in our minds of how the United States would respond to a major new terrorist attack. But the mind of the president is not the only thing to worry about. When one of the central institutions of the American political system simultaneously cracks up and wins the White House, the country’s ability to formulate and implement effective policy will inevitably be damaged.

The same will be true of our ability to call on support from others. On September 10, 2001, no one thought that America was in a profound internal crisis, much less fighting for its political sanity. Apart from kooks, no one thought America deserved—or was somehow asking—to be attacked. No one doubted the value of being our friend. In 2017, in the early days of a Trump administration, all this will have changed. A president who has made hostility to Muslims and other minorities his calling card, who has suggested NATO may be “obsolete,” who boasts that we have our own problems to solve, may find the rest of the world ready to let us do so. Around the table in the Sit Room, no one may say this to the boss. But everyone will know it.

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“I’m betting the Trumpian response would be a lot closer to what Barack Obama might do than Bush 43”

Aaron David Miller is vice president for new initiatives and a distinguished scholar at the Woodrow Wilson International Center for Scholars. His most recent book is The End of Greatness: Why America Can’t Have (and Doesn’t Want) Another Great President.

Politics during a presidential campaign is about telling folks what they’d like to hear; governing is about what they’re likely to get. And Donald Trump the candidate operates in a fantasy world on foreign policy bringing to the debate on America’s role in the world a fantastical mix of isolationist and muscular nationalist rhetoric.

Meanwhile back on planet earth, Donald Trump as president will confront the same gap between words and deeds that faced his predecessors and the constraints that impinge on any president at home and abroad. I fear the unpredictability of a Trump presidency. (I can barely utter those words in close proximity.) Still if I had to wager, I’d bet that in Trump’s case—as for most bullies, and this one highly inexperienced in foreign policy—risk aversion rather than risk readiness will prevail in response to an ISIS style Paris or Brussels attack in the United States.

I know it’s going to come as a shocker, but I’m betting the Trumpian response would be a lot closer to what Barack Obama might do than Bush 43. We’ve seen that movie before Iraq; Patriot Act; waterboarding, torture; tens of thousands of ground forces deployed; trillions expended. Outside of the torture he’s endorsed, Trump has opposed wasting money in the Middle East nation-building; sending large numbers of U.S. troops, etc. I’d expect more air and missile strikes, maybe more special operators to Iraq and Syria in a stepped up campaign to deprive ISIS of territory.

Where I do worry greatly is what Trump might do on the domestic side in the wake of such an attack—his rhetoric on Arab and Muslim Americans, and policies on surveillance and immigration. Remember Denzell Washington in “The Siege” where the U.S. military takes over New York City and rounds up thousands of Arab and Muslims Americans? There’s a Constitution and institutions in this country that will prevent him from going as far as that, but Trump has so far proved to be a divider not a uniter or a reassurer. In the wake of a significant terror attack by, say, ISIS, we need a president who’s tough and wise and who can bring us together not drive us apart; and not play into or fuel the inevitable anger and fear that’s going to be directed at Muslims. Lee Atwater said it best. There’s this small boat which includes a small group of individuals who have the character and stature to be president. That applies doubly during a crisis. And Trump’s not in it.

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“Trump, a thin-skinned malignant narcissist who can leave no slight unavenged … is the candidate most likely to overreact to a terrorist event”

John Gartner is a private-practice psychologist, part-time assistant professor of psychiatry at Johns Hopkins University Medical School and author of In Search of Bill Clinton: A Psychological Biography.

Trump, a thin-skinned malignant narcissist who can leave no slight unavenged, no matter how slight (God help us if Kim Jong-un makes fun of his hands), is the candidate most likely to overreact to a terrorist event or threat in an impulsive, misguided and heavy-handed way that would win us enemies and influence people around the world to hate us. For example, his proposal to “register” all Muslims in America will humiliate a proud people and radicalize scores of young people.

Malignant narcissists are not your garden-variety narcissists. They combine narcissism with paranoia, anti-social traits and a propensity for aggression. Trump sees threats where they don’t exist—like Mexican immigrants who “might be ISIS”—and feels no compunctions about breaking rules, such as those against torture or collective punishment, to lash out at those imaginary threats. The Geneva Convention is for politically correct suckers. The law of the jungle, not the rule of law, is the organizing principle of malignant narcissists. And if they can’t rule the jungle they’ll burn it down.

Malignant narcissism is an untreatable personality disorder, for the simple reason that no one can ever tell the malignant narcissist he is wrong. Anyone who questions a malignant narcissist’s judgment is immediately dismissed as an idiot or attacked as a threat. Anyone who questions their ruthless tactics is belittled as soft and naive. It’s not accidental that Trump has said “my primary consultant is myself.”

The appeal of narcissistic leaders is real and understandable. In America we’ve had a history of charismatic hypomanic narcissists, warm narcissists if you will, like TR and FDR, who were positive forces of nature, leading the country out of hard times by using their larger than life personalities to inspire a faith in America that made us feel larger against our enemies, while single handedly pushing the nation in a more progressive direction that broadened democracy to include the needs and voices of the many. But even malignant narcissists, who concentrate all the power in themselves, can lend strength, inspire confidence and chart a collective direction for their country. Hitler took a dispirited defeated nation in the throws of depression and with the promise to make Germany great again turned it into a world power. But the downsides are unimaginable: Hitler also replaced democracy with dictatorship, tolerance with genocide, and sowed the seeds of his nations destruction with his ruthless will to conquer.

In short, a president Trump is one of the biggest threats imaginable to our national security. His need to appear strong will make us weak. A malignant narcissist is much like a malignant tumor. Sooner or later it will kill the body politic.

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“The nihilistic Trump, who regards human beings as brutish children, might well react to a terror attack like a brutish child”

Michael D’Antonio is author of more than a dozen nonfiction books, including Mortal Sins and Never Enough, Donald Trump and the Pursuit of Success.

Within moments of our first meeting, Donald Trump told me that if he is guided by any principle it is this: “If you hit me, I’ll hit back, ten times harder.” (I came to think of this as the Trump Rule of Ten.) In subsequent meetings he added to what might be called a personal philosophy with references to how much he enjoyed conflict—“I always loved to fight”—and his belief that people are “inherently dishonest.” Add Trump’s frequent references to the viciousness that dwells in the human heart and his belief that character is fixed at roughly age six, and you can imagine of way Trump could respond to a terror attack on America.

The nihilistic Trump, who regards human beings as brutish children, might well react to a terror attack like a brutish child. President Trump would pressure intelligence agencies to immediately identify the source of the attack. Civil liberties may be suspended in the emergency pursuit of information, suspects and conspirators. Those taken into custody would be tortured, if Trump deemed it necessary. Speed would be an important part of the Trump response to terror, so we should not expect much deliberation or consultation with Congress or allies. And given his penchant for disproportional warfare, he would order a massive military response just as soon as he felt confident about a target.

In such a scenario, the destruction of an office tower in New York would be answered with the annihilation of a city controlled by those Trump deemed to have sponsored the attack. To get a sense of how this might work, imagine the Bush administration’s tragedy in Iraq carried out in a matter of weeks, not years. If the targets of such a crude and violent response follow the established script, they would then attack the West on a scale that would make Brussels, and Paris, and San Bernardino seem like rehearsals. As the fight escalates, according to the Trump Rule of Ten, Americans would truly experience the terror the attackers intend.

If the actions of the President Trump that I describe above seem too awful to consider, hope resides in the idea that much of what the man says and does is, to echo a term he recently used on CNN, “show business.” If this is true, then we might discount the bellicose rhetoric and the marginal figures he has named as advisers. However, this wish, that Trump doesn’t mean what he says, is a poor foundation on which to place our confidence in the future. We shouldn’t have to guess about our president’s temper.

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“As a self-professed America Firster, Trump seemingly thinks of statecraft in terms of profit-and-loss. Yet with apologies to Clausewitz, international politics is not the continuation of business by other means”

Andrew Bacevich is author of the new book America’s War for the Greater Middle East: A Military History, to be published on April 5.

Unmoored to principles and precedents, possessing a remarkably shallow grasp of history, Donald Trump is unlikely to demonstrate much by way of the cool calculation that successful crisis management requires. True, the actual exercise of power can educate, as it did in the case of John F. Kennedy, for example. By the time of the Cuban Missile Crisis, JFK’s “pay any price, bear any burden” inclinations had given way to let’s make a deal: my nukes in exchange for yours and let’s not do this again.

Whether Trump is similarly educable stands as an open question. Confronted with some unexpected threat, would he pause to evaluate the precipitating factors? Kennedy did, and it served him well. Or would he give in to an impulse to lash out? That describes the George W. Bush administration’s response to 9/11. To put it another way, would intellect or emotion shape Trump’s approach to making decisions?

More than anything else, of course, Trump prides himself in being the dealmaker par excellence. Yet based on his recent pronouncements—casually proposing to revive the practice of torture, for example, or speculating that Japan and South Korea might consider acquiring nuclear weapons—he appears all but incapable of appreciating the possibility of adverse second order consequences.

True, for anyone running for president, a certain amount of shooting from the hip is to be expected. Trump is hardly the only candidate making bold statements—carpet bomb ISIS, move the U.S. embassy in Israel to Jerusalem on day one. But in most cases such promises are offered less as a serious basis for action than as a way of currying favor with particular constituencies. In Trump’s case, unfortunately, it’s hard to tell if he’s striking a pose or making statements that he intends to be taken seriously. (To be fair, it’s just as hard to interpret various off-the-wall statements made by Trump’s immediate rival Ted Cruz).

As a self-professed America Firster, Trump seemingly thinks of statecraft in terms of profit-and-loss. Yet with apologies to Clausewitz, international politics is not the continuation of business by other means. The object of the exercise is not simply to gain some immediate advantage at the expense of others, but to enhance the freedom, abundance, and security enjoyed by the American people while at the same time promoting conditions that others—allies and adversaries alike—find tolerable.

Surrounding himself with advisers who are somewhat more—what’s the word? seasoned? sane?—might encourage Trump to curb his wilder inclinations. But who in their right mind would sign up to serve in his administration?

Probably people who think like Trump. Now there’s a scary prospect.

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“A 9/11-style attack on U.S. soil would mean that any remaining restraints to the use of weapons of mass destruction … would likely be swiftly swept aside”

Elizabeth Borgwardt is a history professor at Washington University and the author of The Nuremberg Idea, forthcoming from Knopf.

Donald Trump’s March 21 interview with the Washington Post editorial board should make every potential voter’s blood run cold. After noting that ISIS should be knocked out flat, yet indicating that large numbers of U.S. troops should not be involved, Mr. Trump suggested that it was better to be “unpredictable” in the face of U.S. enemies, before twice dodging a question about whether he would advocate the use of tactical nuclear weapons against ISIS. (To be fair, the interview transcript indicates that much more time was spent discussing Mr. Trump’s hand size than anything to do with nuclear weapons.)

All this was before the attacks in Belgium; my sense is that a 9/11-style attack on U.S. soil would mean that any remaining restraints to the use of weapons of mass destruction—including nuclear weapons—would likely be swiftly swept aside.

General Douglas MacArthur had notoriously floated the idea of using nuclear weapons against China in the Korean conflict (1950-53) when he was concerned about Chinese moves to support North Korean aggression. In posthumously published interviews, MacArthur said that he could have won the war in ten days: “I would have dropped 30 or so atomic bombs … strung across the neck of Manchuria. For at least 60 years there could have been no land invasion of Korea from the North.”

Part of MacArthur’s logic was that the United States would have needed to fight communist China eventually, so it would be best to nuke them while they were still weak, recovering from World War II and the Chinese Revolution (1949), as opposed to fighting them later after they had become much stronger. “That makes sense to me!” opined a Trump backer with whom I recently spoke on this topic. And yet, I offered, most Americans today are probably pretty happy that we didn’t use nuclear weapons against China in the Korean war, or would be if they knew anything about that historical interlude. “I guess,” he said. “But why not press your advantage when you have one?”

I offer this example because my sense is that in a putative Trump administration, “the gloves would be off” and all barriers—including public opinion—to the first use of various kinds of weapons of mass destruction would likely be at an all-time low. Bruce Cumings, the leading U.S. historian of Korea, has commented on the MacArthur incident in an analysis from back in 2004. Cumings noted that “MacArthur sounds like a warmongering lunatic” for advocating the use of nuclear weapons, but also explained that, astonishing as it might seem, the general actually had some support for his outlandish proposal.

Cumings also noted that MacArthur’s conduct, quite appropriately, contributed to the celebrated war hero’s dismissal by President Truman. But that was then.

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“Trump’s foreign policy inexperience and the proven tendency of one thing to lead to another in military interventions could easily mean a protracted U.S. involvement in a ground war in Syria”

Paul Pillar is nonresident senior fellow at the Brookings Institution and at the Center for Security Studies at Georgetown University. From 2000 to 2005, as the national intelligence officer for the Near East and South Asia, he was in charge of the analysis of those regions for the CIA and all other American intelligence agencies.

In a Trump presidency, the potentially moderating influence of the national security establishment will be far less powerful than Trump’s own ideas and the political demands of a scared, fired-up public in the aftermath of a terrorist attack like 9/11.

If we know one thing about Trump, it’s his talent for providing an outlet for cruder, simpler and more emotional demands of the general public—and we will likely see that talent in his counterterrorism policies in the days following an attack on the scale of 9/11. Trump’s statements about the use of torture have been specific enough that after an attack he would feel almost obliged to re-institute it in the military and intelligence agencies if he had not done so already. There would be significant resistance to doing so, of course, and given how the issue has been viewed and discussed in the past couple of years it may seem unlikely that Trump would succeed in making this change. But current public and congressional views of the issue are much different from the views that prevailed in the immediate aftermath of 9/11. In the aftermath of another 9/11-type attack, public moods and thus tolerance of torture are likely to revert to what they were back then.

Assuming any connection at all could be made between the attack and a foreign location—such as the ISIL-controlled enclave in Syria—a Trump administration would launch a major military assault on the ostensibly relevant foreign targets. Although some of Trump’s statements during the campaign suggest an aversion to large ground wars and to anything that smacks of nation-building, the subsequent political and operational momentum may overtake the aversion. Trump’s foreign policy inexperience and the proven tendency of one thing to lead to another in military interventions could easily mean a protracted U.S. involvement in a ground war in Syria.

President Trump’s relations with allies and other foreign states in the aftermath of an attack would resemble the “for us or for the terrorists” attitude of the George W. Bush administration but with the addition of a generous dose of Trumpian bombast. There would be much wincing in foreign capitals as governments tried to strike a balance between supporting an America that had just been attacked and not appearing to be bullied by the man in the White House.

The rest of what would be a distinctively Trump response to an attack would be felt domestically. This would be the occasion for a President Trump to do whatever he had not already done in restricting immigration. Beyond that, candidate Trump has given us little specific to go on, but it is likely that the status of Muslims in America and their relations with fellow citizens would become as delicate and fraught as they ever have been. Islamophobia will likely surge and relationships between Muslim communities and police will likely worsen. A President Trump would be more likely to exacerbate than to smooth the fears and suspicions involved.

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“As president, Mr. Trump would indeed project strength … But he would be incapable of … thoughtful self-restraint”

Joe Burgo is the author of several books, including The Narcissist You Know: Defending Yourself Against Extreme Narcissists in an All-About-Me Age.

If he were president, Mr. Trump would respond to a 9/11-type terrorist attack much as he has responded to personal attacks throughout the campaign. He would be preoccupied with his self-image and the need to come across as a “winner” and not a “loser” upon the world stage. On some level, he would experience the attack as an assault on his own stature, a blow to his grandiose self-image, and would likely respond with reflexive violence, as he usually does when attacked. In this case, rather than verbal assaults, it might involve massive “carpet bombings” without adequate intelligence, and an immediate declaration of war.

In times of crisis, frightened citizens need their president to project an image of strength and confidence; at the same time, they need him to remain thoughtful and not respond in a reactionary, thoughtless way that might make matters worse. As president, Mr. Trump would indeed project strength by presenting himself as a take-charge strongman who knows how to deal with terrorists. But he would be incapable of the kind of thoughtful self-restraint we need from our president in a time of crisis: For Trump, an attack requires an immediate and overwhelming assault on the perceived source of the attack.

When Megyn Kelly criticized him, he responded with outsized contempt, indignation and blame, the “weapons” he consistently uses to annihilate his enemies. It’s frightening to imagine what he would do to annihilate the source of a terrorist attack were he to have a nuclear arsenal at his disposal.

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“Trump has given no suggestion that he would be more prudent [than Bush]. Nor, for that matter, has Ted Cruz”

Stephen Kinzer is a visiting fellow at the Watson Institute for International Studies at Brown University. His books include All the Shah's Men: An American Coup and the Roots of Middle East Terror and Reset: Iran, Turkey, and America's Future.

Even imagining the craziness that might seize President Trump in the wake of a terror attack is frightening. Most likely, his response would be at least as irrational as what George W. Bush did after 9/11. Bush took radical steps that ultimately harmed the United States far more profoundly than the attack itself. Trump has given no suggestion that he would be more prudent. Nor, for that matter, has Ted Cruz.

More interesting is the effect that Trump’s rhetoric might have in attracting an attack. Wise terror strategists—and there evidently are some—realize that over-reaction to an attack on the United States would be in their interest. A crackdown that restricted the civil liberties of American Muslims would allow militants to paint the United States as a relentless enemy of Islam. So would an American military assault in the Middle East, especially if it were carried out with ground troops. These would be godsends to terrorist recruiters.

If the next American president projects an air of measured calm, and does not seem ready to lash out wildly if provoked by a terror attack, such an attack will be less likely. But if President Trump were in power, setting off a bomb on the Washington Mall would be a great temptation. Terror groups in the Middle East, especially ISIS, are eager to bait the United States into another self-defeating disaster like the Iraq War. Trump seems ready to be baited—so why not try?

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“If history is any lesson, Trump would alienate American allies … undermining U.S. efforts to work together with other countries to combat transnational terrorism”

Mary Dudziak is professor of law at Emory University and chair in American law and governance at the Library of Congress.

In light of Donald Trump’s tendency to react to problems by blaming minority groups, including Muslims, and promoting torture, we might expect more of the same, perhaps at a greater volume, than we’ve seen so far.

That would serve Trump and the nation poorly. The way the United States treats minority groups has had an impact on U.S. foreign relations in the past, and would be a problem in a Trump presidency. President Dwight D. Eisenhower was just one president who had to confront the impact of prejudice against African Americans, and civil rights-related unrest, on America’s image around the world. When white mobs protested the integration of nine African American students at Little Rock, Arkansas’ Central High School in 1957, it became a major international story. American discrimination was condemned around the world. It was also used against American interests, as the Soviet Union featured U.S. racism as a principal theme in its anti-U.S. propaganda. Eisenhower had not supported judicial action to integrate schools; but prodded by his secretary of state and others, he sent federal troops to Little Rock. One of the reasons for his turnabout was his hope to restore the global image of American democracy, and keep American racism from harming the nation’s Cold War mission.

The Trump campaign has already generated international criticism for its hostility to Muslims and Mexican immigrants. His inflammatory calls for the use of torture would damage U.S. credibility on human rights. If history is any lesson, Trump would alienate American allies with these policies, undermining U.S. efforts to work together with other countries to combat transnational terrorism.

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“There would be no telegraphing of policy decisions to allow those responsible to adjust. And there would be public justifications about ‘limits’ and ‘proportionality’”

Stanley Renshon is a political science professor at the City University of New York, is a certified psychoanalyst and the author of 15 books, most recently National Security in the Obama Administration: Reassessing the Bush Doctrine.

Trump would be angry, much as George W. Bush was after the 9 /11 attacks, but much less methodical. He would order all available assistance to the victims, take to the airwaves to assure the American people that the attack would not go un-avenged and then proceed to do something dramatic, public and lethal.

There would be with Mr. Trump no publically drawn red lines that he takes pride later in not crossing. There would be no telegraphing of policy decisions to allow those responsible to adjust. And there would be public justifications about “limits” and “proportionality.”

At minimum, the response would involve dramatic airstrikes against previously off-limit targets—oil rigs, training grounds and even targets within urban areas, if necessary—and ramped-up commando raids against those enemies and their supporters, primarily in Syria, but world-wide as well. If the attacks were committed by immigrants or Americans, I wouldn’t rule out his asking Congress for much tighter controls on immigration and even the loss of legal status and citizenship for any supporters found to be involved. The intended message would be stark: attack us and you and those who support you will pay an unbearable price.

This rough response would very likely provide some comfort to Americans, as George W. Bush’s strikes against the Afghan government and his subsequent strategy of preemptive attacks against imminent threats did after 9/11. It would also signal to America’s allies and opponents that Mr. Trump’s view that the United States should fight back against being taken advantage of were not mere words, but reflected a real emotional conviction. Though kumbaya internationalists might think differently, this might have a sobering and therefore salutary effect on both free-riding allies and ever-watchful enemies.

That said, an important question that will follow is this: after his display of resolve and revenge, what better policies will he put into to place, domestically and with our allies abroad, to lessen the risks of further attacks going forward? That, not his first and understandable impulse, will be a true measure of his presidency and his maturity as a leader and a president.

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“Trump appears to employ a much more externalizing style. … When he is threatened his primary response seems to be to fight back”

W. Keith Campbell is the head of the Department of Psychology at the University of Georgia

In the case of threat, people have two general patterns of responding—externalizing and internalizing. Externalizing involves responding boldly and aggressively to the source of the threat; internalizing involves responding by turning inward, including feeling depressed or blaming oneself for the threat.

Trump appears to employ a much more externalizing style. (A caveat: My answer is highly speculative and based on general psychological models and my observations of Donald Trump on the campaign trail alone.) When he is threatened his primary response seems to be to fight back. He does this even in the case of threats that seem purely adolescent—when the size of his fingers were challenged, for example.

If, in fact, his aggressive style applies to threats to himself, the next question is whether that style would apply to threats beyond him. We saw a recent incident where supporters of an opposing campaign used Trump’s wife in a hostile campaign message. Trump’s response on Twitter was to make what appeared to be a veiled threat against the opposing candidate’s wife. So, in this case he acted aggressively against a threat to his wife. It is plausible, then, that he would act in the same way if America were attacked or threatened and he were president. His reaction would be to attack the source of the threat. We saw that with his Brussels response, when he immediately called for tougher border control and anti-terror measures.

Both internalizing and externalizing have a place in good leadership. Internalizing can be seen as thoughtful but also feckless. Externalizing can be seen as strong but also impulsive. Outside forces know that if they provoke an externalizing leader they are likely in for a fight. Ideally, this will lead to less provocation (this is part of the “peace through strength” model). But while this approach works well when dealing with other nations, it is less certain when dealing with nationless terrorists who might actually be looking to provoke an aggressive military response.

Trump does not appear to internalize very much about personal attacks, and, by the same token, I imagine he wouldn’t apologize for potentially harmful aspects of U.S. foreign policy in the aftermath of a terrorist attack, either. However, it’s possible that his aggressive mentality might be tempered by more internalizing officials at the Pentagon and State Department.