The decision to move the American embassy to Jerusalem makes a war in Korea more likely. Not because there is any direct connection between the two, nor because it was a bad idea, recognizing as it did the simple fact that the western part of Jerusalem has been Israel’s capital for over 70 years and will most assuredly remain so. The dangerous bit, rather, was when pundits and diplomats wrung their hands and predicted calamity and (far more predictably) nothing happened. The Arab street grumbled, while Cairo, Riyadh, and Abu Dhabi looked the other way, and Donald Trump could be forgiven for thinking that his instincts had been proven entirely correct.

And therein lies the danger. As we can see from the irritable id that manifests itself in his tweets, Trump believes that he has been an exceptionally successful president, who deserves credit for the absence of deaths from plane crashes, a soaring stock market, and a tax cut rammed through on a completely partisan basis by a Republican majority that has thirsted for little else for decades. Those who made fun of his claims that he is smarter than his generals and that there is no need for a fully staffed State Department because he is around, or mocked his boasts that his nuclear button is bigger and better than Kim Jung Un’s, should stifle their chuckles. This is serious. The president feels vindicated, smart, and self-confident beyond the outlandish egotism of his campaign days last year.

This is serious first and foremost because the North Korean threat is serious. National Security Adviser H.R. McMaster is correct when he notes that the North Koreans have always been willing to sell anything—literally anything—to anybody with the hard cash to buy it. That will be true of their nuclear weapons. It is indeed true that Pyongyang is on the verge of acquiring the ability to obliterate Los Angeles, and eventually Washington. It is certain that this regime has shown no respect for any international norms, let alone international law; that it has committed murder; that it lives in a psychotic cocoon of its own making; and that it will stop at nothing. And it is true, finally, that this dangerous circumstance is not of Trump’s making: It is rather the consequence of policies that bought time and offered no idea what to do with the time that was purchased through shifting combinations of diplomacy, bribes, sanctions, and skullduggery.

Any administration faced with these facts, and at this technological moment in the North Korean program, would have weighed carefully the possibility of a preventive war —it would be the prudent strategic thing to do. And then they would have walked away from it. A deliberately initiated war still runs the risk of a humanitarian disaster, because, as everyone now realizes, Seoul is within range of thousands of North Korean artillery tubes and rocket batteries. Hundreds of thousands of civilians, including American expats and dependents, would perish in the war that could be unleashed. Even assuming some magical technologies that enable the U.S. to disarm North Korea and decapitate its leadership, who is to say that the ensuing war would not have its way even so?

The consequences of preventive war—a war deliberately initiated by the United States or launched as a result of provocations by one side or both that then escalates—go far beyond this. South Korea, within the memory of people now living, has gone from being poorer than most African countries in 1950 to becoming a first-world technological and economic power house. Could South Koreans forgive the Americans for the slaughter of their citizens and the devastation of their cities because of weapons aimed a hemisphere away? Would the Chinese meekly accept an American conquest of North Korea, or even simply the elimination of the Kim dynasty? Or are they more likely to pour troops, aircraft, and missiles into the Korean peninsula and to warn the Americans off? And where might that lead?

To judge by his public statements, McMaster, like UN ambassador Nikki Haley, is hard over on the notion that North Korea has to be denuclearized, be it by peaceful surrender or by force. He has used the words “preventive war” on several occasions. In so doing he is, of course, echoing the president, but it is reasonable to think that he agrees with the basic idea. And that would not be entirely surprising: His duty is to ensure the security of the United States, and North Korea’s intercontinental ballistic missiles would undoubtedly be a threat to that.

What the president’s advisers may not fully appreciate are the political perils of taking such a hazardous course. The fact is that a majority of the American people seem to believe that many words coming out of the president’s mouth are lies. That will not change when he sits behind the Resolute desk and tries to explain why he has launched a Korean war. Trump’s advisers may think that their credibility may substitute for their boss’s lack of it, but they are wrong there too, for, inevitably, their reputations for integrity have been tainted by their own Trumpian pronouncements. Abroad, some governments—Australia and Japan, for example—may feel compelled to side with the Americans. But they too will discover that their populations’ mistrust and disgust towards the American president will undermine their participation in a war. And when all these forces come together, the political firestorms may sweep away long-standing international relationships as well as myriads of Korean and American lives.

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There are sounds, for those who can hear them, of the preliminary and muffled drumbeats of war. The Chinese are reported to be preparing refugee camps along North Korean border. Resources are being shifted to observe and analyze the North Korean military. Mundane logistical processes of moving, stockpiling and updating critical items and preparing military personnel are under way. Only the biggest indicator—the evacuation of American dependents from South Korea—has yet to flash red, but, in the interest of surprise, that may not happen. America’s circumspect and statesmanlike Secretary of Defense, James Mattis, talks ominously of storm clouds gathering over Korea, while the commandant of the Marine Corps simply says “I hope I’m wrong, but there’s a war coming.”

Maybe nothing will happen. Maybe Donald Trump, he of the five draft deferments during the Vietnam war, will flinch from launching a war as commander in chief, in which case the United States will merely suffer an epic humiliation as it retreats from as big a red line as a president has ever drawn. Still, lots of people have an interest in war. For Russia, the opportunity to set the United States and China against each other over Korea is a dream come true. For narrow-minded American strategists, it is the only way of cutting the North Korean nuclear Gordian knot. For Kim Jong Un peeking over the edge of the precipice may cause South Korea to break with the Americans, or the Chinese to fight them. For Donald Trump it may be a moment of glory, a dramatic vindication of campaign promises, and an opportunity to distract American minds from Robert Mueller’s investigation of his campaign’s ties to the Russians. And so threats and bluster may turn into violent realities. And if they do, not tomorrow or the next day, but some time in 2018, a Second Korean War could very well make it one of those years in which history swings on its hinge.