Donald Trump has spoken to the world and left us feeling what? Relieved and reassured that the leader of the world’s largest power understands his responsibilities to shelter us from calamity at a time of unusual turmoil and crisis? No. We are left on edge. We are left rattled.

Just as Trump has enjoyed upending Washington he is now revelling in chipping the crockery of international diplomacy. Could the United Nations use a breeze to clear some of its bureaucratic cobwebs and cautious timidity? It could. But an American president threatening to “totally destroy” an entire nation is more than a breeze. That’s not plain talking, its plain scary.

Before he got onto eviscerating North Korea and the “Rocket Man” who runs it – a childish monicker that would have been removed in any sober editing of his maiden address to the United Nations – and then Iran and Venezuela, Trump did a brief approximation of statesmanship. “We meet at a time of immense promise and great peril,” he offered. “It is up to us whether we will lift the world to new heights or let it fall into a valley of disrepair.”

He graciously thanked all those countries that have given aid to hurricane victims. He evoked the Marshall Plan, the US-funding rebuilding of western Europe after the end of the Second World War, as a model of global brotherhood and spoke of what he called his three pillars of peace for all UN member nations: “Sovereignty, security, and prosperity for themselves, and for the world.”​ So far so good. The UN’s vision of itself is the pursuit of human rights, peace and security, and development. Kind of the same.

Except that human rights is missing from Trump’s. But that fits with his other theme up there at the UN lectern. His America will be different from that of Obama, Bush and Clinton – or pretty much any president you can name since Truman – because it won’t be telling others how to run their affairs. No nation-building, no finger-wagging. “In America we do not seek to impose our way of life on anyone but rather let it shine as an example for everyone to watch,” he said.

But stop the tape there for a second. It will be a little deeper into the speech that Trump repudiates that promise precisely identifying nations he thinks aren’t behaving as they should. But first that thing about America setting an example. Yes, well. Not everyone, perhaps, will be straining to follow the example of his America – religious-based immigration bans, lowering the gates on refugees, building border walls, turning its back on climate and trade treaties.

That was a point that had been made in less-than-subtle terms by the new UN Secretary General, Antonio Guterres, who took to the lectern a little earlier. “Trust within and among countries is being riven down by those who demonise and divide,” he said. Trump was not in the room at the time. “Instead of closed doors and open hostility, we need to reestablish the integrity of the refugee protection regime and the simple decency of human compassion.”

“If the righteous many do not confront the wicked few, then evil will triumph,” Trump later intoned. A nice phrase reminiscent of George W’s “axis of evil” of 15 years ago. But then he went Elton John on North Korea and its leader Kim Jong-un. “The United States has great strength and patience, but if it is forced to defend itself and its allies, we will have no choice but to totally destroy North Korea,“ he said, triggering an audible shudder in the giant chamber, if not around the world. “Rocket Man is on a suicide mission for himself and for his regime.”

Cue more shudders on Iran. Trump left no doubt what he thinks of the deal done to constrain its nuclear programme. He doesn’t like it and he’s aching to tear it up, though he has made no formal decision yet. If he does, everyone else who was involved in negotiating it, including Britain and the EU, will be appalled. The UN’s own nuclear inspectors have said Iran is abiding by the agreement. Only Benjamin Netanyahu of Israel will have liked this passage. Actually he liked the whole speech, which tells you something. “In over 30 years in my experience with the UN, I never heard a bolder or more courageous speech.“

Or more filled with contradictions or arrogant posturing. How’s that no-imposition thing going for you with Venezuela, sir? “The problem in Venezuela is not that socialism has been poorly implemented but that socialism has been faithfully implemented,” he said. Ah, yes. America has a bit of a history of not liking socialism when practised by its neighbours. “From the Soviet Union to Cuba, Venezuela – wherever through socialism or communism has been adopted, it has delivered anguish, devastation and failure,” he added. If President Nicolas Maduro doesn’t mend his ways, the US, which has already hit Caracas with sanctions, “will be prepared to take further action”.

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But there was a more fundamental problem with this speech. Trump used it not just to defend his America First agenda at home, but he pleaded with every nation to take the same path. This is a recipe not for world harmony but for jungle competition and conflict and is uniquely opposed to everything the UN stands for. “I will always put America first just like you, the leaders of your countries, should put your countries first,” Trump said. He even appealed for a common reawakening of national patriotism. “Are we still patriots?”