What America called 9/11, the rest of the world knew as 11/9. But the rest of the world learned to call the terrorist attacks in the United States the American way. The date Americans call 11/9 is called 9/11 in the rest of the world, and elsewhere in the world it feels a bit like that too.

This is not to undermine the horror of the attacks of 2001 in which thousands died, but to note the cataclysmic and transformative impact of the US presidential election. The result changes America; it changes the way we look at politics and the world around us. The main difference is that while 2001 wasn’t anticipated, globalised markets knew what Trump stood for. The world knew what he thought of free trade (tear up agreements, not open markets), foreign investments (jobs in America, not elsewhere), free movement of people (building walls, not bridges) – things that matter more to the markets than his bigotry, misogyny, arrogance, recklessness, and vindictiveness, which have far more lasting consequences on society. And he presents a deeply unsettling picture.

Those who voted for him did so knowing what he represented and what he thought of others. In his speech in New York he sounded gracious, as he tried to reach out to those he insulted, saying he would become the president for all Americans. But if he carries on in that vein, he will lose the support of the people he has rallied. If he belies the expectations of those core supporters, it will only stoke their anger. And if he stays true to the obnoxious messages his campaign personified, his leadership can have devastating consequences not only for Americans, but also for the world. The world is in for an unpredictable and very rough ride.

Trump is his own man; he ran the campaign on his terms; he shunned the establishment, even ridiculed it – not only the establishment in Washington, but also of the party whose candidate he chose to become. It would be foolish – and brave – to predict what he would do. Having shunned the party hierarchy and orthodoxy, he is going to have to build a team from those who crossed the road when they saw him. That will make him a uniquely powerful and uniquely isolated president.

Trump is singularly divisive; his supporters – some even on networks – are triumphant, some of them arrogantly so. It is their victory; do not expect grace from nationalists who shout “USA USA," who, until an hour ago, thought the objective of the campaign was to “lock her up."

Americans and their well-wishers will want to say and believe that there is an essential decency among American people; that those who voted for Trump did not embrace his positions. That’s not how it sounds here, across the pond in London, and elsewhere in the world. Voting in Trump isn’t the fault of every individual American, but well-wishers of American democracy will need to reflect hard on what happened to that collective will. In that, the United States isn’t alone; bigots of various hues have come to power in other parts of the world in recent years – America was meant to buck that trend. Instead almost half of Americans have chosen to be part of that trend. From being the glorious exception, America has become part of the new normal. Trump didn’t run a campaign that was inclusive and which sought fairness – he ran a campaign that was built on bitterness, divisiveness, and anger. The exceptionalism he sought is of one rule for him, another for others.

That divisiveness must be challenged by decent Americans, and there are millions of them, and others around the world who want to believe that the “shining city on a hill" is neither wishful thinking, nor propaganda. Reclaiming decency in public life, reasserting the rights of the vulnerable, reinforcing commitment to a fair democracy are noble, worthy goals – it is a battle Americans must join and must win.

Otherwise, the world gets inverted, and 11/9 becomes 9/11.