Who still wants to bemoan the demise of the “special relationship”? Enter Donald Trump, Britain’s latest best friend. “I think Brexit is going to end up being a great thing,” he assured the UK by way of the Times on Monday. Then he held out a big, juicy bone to Theresa May – a trade deal with the United States. “We’re gonna work very hard to get it done quickly, good for both sides.”

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So back to the glory days of the 20th century when America and Britain went after the Hun and Adolf Hitler – and won. (We’ll forget how Eisenhower expelled Britain from its old Middle East bailiwick during the 1956 Suez war and Ronald Reagan’s longish initial refusal to support Margaret Thatcher in the Falklands war against Argentina.)

More candy for Little England. While presenting himself as a “big fan of the UK,” the president-elect bestowed faint praise on Angela Merkel, Germany’s eternal chancellor looking at her fourth term this fall. “Yeah,” she is “by far one of the most important leaders.” And he “liked” and “respected” her.

But then, Trump bared his fangs. Her open-door policy on Syrian refugees was a “catastrophic mistake”, a term he repeated thrice. How could she give up control of her country’s borders, “taking in all those illegals?” Would he vote for Merkel in the autumn? asked Kai Diekmann, his German co-interviewer. Well, he didn’t know. This barb falls just short of a vote of no confidence.

Nor were the Germans amused by Trump’s next broadside that targeted Germany as master of Europe. “Look at the European Union and it’s Germany. Basically a vehicle for Germany.” Of course, Berlin is number one by dint of economic clout and strategic position. But we don’t utter such inconvenient truths in polite western society. Sticking to protocol, Merkel’s spokesman did not fire back. He just noted that his boss had read the interview with “great interest”. Make that: you are out of bounds, Mr Trump.

The Brexiteers got more pats on the back. Without the flood of refugees, “you wouldn’t have a Brexit,” Trump claimed, insisting that “people want their own identity”. This is why “others will leave” the EU. Instead of being left behind, the UK actually represented the future. He would not put his money on the euro that “will be very hard to keep together”.

No more pieties from this president who thus put paid to the Europhile mantras of his predecessors from Harry S Truman down. To the US, Trump opined, “it does not matter” whether the EU lives or dies. Nato, the proudest achievement of US diplomacy, is on the block, too.

Does this sound like a remake of the 1920s and 1930s? It does

It was just empty campaign rhetoric, most seasoned observers, including this one, shrugged when Trump declared the alliance “obsolete”, adding: pay up, or we pull out. We were wrong, as we have always been on The Donald, who reaffirmed precisely these slogans in his tête-à-tête with the Times and Germany’s Bild. And yes, he will cosy up to Russia’s Vladimir Putin, telegraphing his willingness to lift sanctions imposed after the Crimean grab.

Take that, Mrs Merkel! She is the one European leader who has stood fast on the sanctions. So let’s stop kidding ourselves. Trump means what he tweets. He won’t shout it out in his inauguration address on Thursday; such speeches are given to sonorous invocations of America’s glorious past and future. But here are the bare bones of Trumpist policy, all of them hard to swallow for Europe and the rest.

First, a deal with Russia that leaves the Europeans twisting in the wind. The purpose of such a twosome is a hands-on alliance against Isis and a tacit one against China to stop its forward march in the Pacific. Second, indifference to Europe and Nato, the two pillars of American grand strategy for 70 years.

Third, let’s put the axe to the liberal trading system the United States built and safeguarded ever since the Bretton Woods order, from which the International Monetary Fund, the World Bank and the World Trade Organisation grew, was established in 1944. Finally, raise high the walls of the nation state in order to keep out goods and people, and keep in capital and jobs.

Does this sound like a remake of the 1920s and 1930s? It does – 100 years later. The first world war ended Globalisation 1.0, circa 1850 to 1914, Trump promises to bring down Globalisation 2.0, born in the 1970s.

How could he possibly pull it off, given that economic and financial integration from Berlin to Beijing has increased a hundredfold since then? Autarky and protectionism make no economic sense, but guess what? Trump, for all his inchoate tweets, has already succeeded in shifting the terms of the debate. He has validated Brexitism and populism that unite left and right in common resentment.

Hasn’t the liberal order enriched the few and impoverished the rest? This is what we hear from Stockholm to San Francisco – never mind the fabulous wealth created around the world. Aren’t those foreigners stealing our jobs while destroying our “own identity”, as Trump has it? Digital automation is the real culprit. And why not gang up with Putin against Isis? Because Vladimir I has far larger strategic fish to fry, and all of them in order to weaken the United States and Europe.

Won’t reality bite? Yes, it will. But the 20th century whispers that it may not bite in time, as the depression and the rise of the Pied Pipers of authoritarianism suggest. In the next four years, Trump can do impressive damage. The upside today is that the demagogues of the 1930s did not have to stand for re-election.