The words “WE ARE ALLIES” are emblazoned in two-foot yellow and white letters on fences around the Nato headquarters in Brussels, in anticipation of Wednesday’s summit.



After nearly seven decades of the most successful alliance in world history, this sort of reminder should not be necessary. But given the events of the past year and a half, there is little doubt about what this message is meant to say and to whom.

Donald Trump will be in Brussels for the summit next week and he is showing every intention of disrupting any attempt at consensus and solidarity.

“I’ll tell Nato, you got to start paying your bills,” Trump told a wildly cheering crowd in Montana on Thursday. The president pondered aloud about the value for the US in paying for the collective defence of Germany.

He said he told Germany’s chancellor, Angela Merkel: “You know Angela, I can’t guarantee it, but we’re protecting you and it means a lot more to you than protecting us because I don’t know how much protection we get by protecting you.”

The denigration of Nato and the EU, longstanding US allies, has become about as common in the US president’s oratory as his praise for autocrats like Kim Jong-un, and Vladimir Putin, who he will meet in Helsinki on 16 July.

“‘You know – President Putin is KGB’ and this and that,” Trump said, referencing criticisms of his relationship with the Russian leader. “You know, Putin’s fine. He’s fine. We’re all fine. We’re people.”

The US ambassador to Nato, Kay Bailey Hutchison, briefed journalists this week in an attempt to provide a more orthodox narrative, insisting that the Nato alliance was firm and the US would stand in solidarity with its western partners in holding Russia to account for its actions in Ukraine, and its meddling in western elections and alleged use of nerve agent in the UK.

But nobody knows what Trump will say in Brussels or Helsinki, or during his UK trip in between. As he demonstrated after the June G7 summit in Quebec, he can trigger a crisis in western cohesion with just a few off-the-cuff jibes aimed at old allies.

Facebook Twitter Pinterest Donald Trump speaks during a campaign rally in Great Falls, Montana, on Thursday: ‘You know, Putin’s fine.’ Photograph: Justin Sullivan/Getty Images

Hitherto US and European officials have uniformly sought to play down the significance of Trump’s antics, insisting that the underlying sinews of the Atlantic alliance are strong. The implication is that Trump has come like a bolt from the blue and will eventually go, while the interlocking security institutions of the west and its common values will outlast him.

However, some western leaders and senior officials are beginning to wonder whether this somewhat complacent assessment is still valid. After all, they point out, Trump is not yelling into a void. When he trashed Nato in Montana, thousands of people yelled their approval. He won the 2016 election and maintains a 90% approval rating among Republicans because he has tapped into a deeply buried reflex in American politics.

In that case, the pessimists argue, perhaps Trump is not the exception, an anomaly in transatlantic progress. Maybe Nato and transatlanticism itself are the anomalies and that US suspicion of and disengagement from Europe are the norm.

“What is on the table right now, in a sort of brutal way is a real problem is not created by President Trump and will not vanish at the end of the term or terms of President Trump,” a senior European official said. “The transatlantic relationship that all of us around the table consider as a given – is not a given.”

The signs were already there during Barack Obama’s administration, this worried official argued. Obama too sought to reorient the focus of US foreign policy from Europe, and towards Asia. He just did not express his disengagement as crudely and rudely as Trump.

“The presidents have understood the fatigue of the Americans towards foreign involvement, in their own very different way,” the official said.

“I think that most Europeans are dreaming that after the term of Trump we will go back to business as usual,” he added, making it clear he thought that was not going to happen. “For the Europeans it is quite a wake-up call. For the Europeans suddenly, their world is shattered.”

For most of its history, the US has sought to avoid entanglement in Europe, and more or less succeeded from independence in 1776 until 1917 and the country’s reluctant entrance into the first world war. Even then, most Americans were keen to leave again as soon as possible. Congress turned its back on President Woodrow Wilson’s international ideals and refused to ratify the Versailles peace treaty or to allow the US to join the new League of Nations.

Congress was just as resistant to being sucked into the second world war, and the US could well have sat on the sidelines had Japan not attacked Pearl Harbor in 1941, and then Germany declared war on the US four days later.

When the second world war was over in 1945, Americans again made plans to pull out, demobilising 90% of their troops. But over the next two years it became increasingly clear European states were not going to recover economically without US help and that Stalin’s Soviet Union was looming as a global threat. So the US stayed in Europe, rebuilding Germany, and forming Nato.

Facebook Twitter Pinterest President Harry S Truman signs the north Atlantic treaty which marked the beginning of Nato. Photograph: Hulton Getty

Now Europe is mostly prosperous, and the Soviet Union has gone. A revanchist Russia has taken its place, but it is a far punier power, with only the fifth biggest economy in Europe.

“Russia is not an existential threat. It’s not felt in London, Paris or Rome as an existential threat. It’s not a unifying threat,” the senior European official said.

With the cold war conditions that persuaded the US to stay engaged in Europe now in the past, some argue that it is inevitable Americans would at some point reconsider their role.

“After 1919 and 1945 we had these huge debates on should we stay in Europe or should we go home,” said the US historian Walter Russell Mead.

“After 1990 there was very little debate. The assumption was that we would double down on the world order building agenda that we applied to the west in the cold war – but we’d now do that globally. We never had that debate. So I think we’re having it now.”

Mead views Trump and his supporters as a throwback to an earlier school of US foreign policy, embodied by Andrew Jackson, who he argues was the country’s first populist president. Jacksonians do not see the republic as a set of ideals but as the nation state of the (white) American people. Jacksonian foreign policy is focused on defending that nation state against malign influences and the cosmopolitan impulses of the elites.

Within days of his inauguration in January 2017, Trump hung a portrait of Jackson, known as the “Indian killer” for his brutal campaigns against Native Americans, in the Oval Office.

The new president’s chief strategist at the time, Steve Bannon, called Mead to tell him that his writings on the Jacksonian tradition in his 2001 book, Special Providence, had inspired the decision to put Jackson in a place of honour in the new White House. He saw Trump as reviving the Jacksonian revolt against cosmopolitan elites. Bannon is long gone, but the portrait of Jackson is still hanging in the White House.

Facebook Twitter Pinterest Donald Trump sits in the Oval Office beneath the portrait of President Andrew Jackson, a populist seen by some as a model for his presidency. Photograph: Alex Brandon/AP

Mead does not argue that Trump’s electoral victory and his readiness to rewrite the tenets of US foreign policy mean that Jacksonian thinking is now dominant. It has about 30-40% of popular support – “not a majority but a significant group”, he said.

The idea that Trump’s ascendancy reflects a reversion back to an earlier American norm is controversial. Many political analysts and historians argue it projects a coherence on to the president’s foreign policy impulses that is not there in reality.

Dan Drezner, international politics professor at Tufts University, argues that what unites the US and Europe in the modern world will ultimately prove far stronger than Trump’s divisive influence.

“These are the twin pillars of liberal democracies. These are continents and countries and associations that have a lot more in common than they do not, Drezner said. “The notion that Nato is going to split asunder I think is absurd.”

Even as Trump rails against Nato, his administration – the Pentagon in particular – has been boosting its commitment to the alliance in resources and troops deployed on its eastern flank. This month’s summit will see the creation of two new commands, one on the US east coast to oversee the protection of transatlantic sea lanes, and another in Germany to run logistics to ensure that the alliance can reinforce quickly when threatened.

The new commitments reflect the atlanticist convictions of the US military and diplomatic corps, who may well be seeking to compensate for Trump’s anti-Nato rhetoric.

“It’s never just one or the other,” Margaret MacMillan, a Canadian historian and Oxford University professor, said. “The idea that there is a default mode of being involved or a default mode of not being involved is too bipolar. It’s much more complex.”

However, MacMillan added, even if Trump does not represent a once-and-for-all shift in US foreign policy, that does not mean his anti-European rhetoric and embrace of dictators is not having a long-term corrosive effect on transatlantic relations. She said: “I think Trump is doing an awful lot of damage and these things are not easily undone.”