Dangerous, foolish, irrational, scary, terrifying, irresponsible, a clown, a disaster. These are just some of the words used to describe the prospect of a Donald Trump presidency by politicians, diplomats and analysts around the world.

As the businessman gave his first major policy address since becoming frontrunner for the Republican presidential nomination on Wednesday, Guardian correspondents in Washington and around the globe asked the international community whether it was prepared for the swaggering billionaire to occupy the White House.

Many said they still cannot believe the nation that elected its first black president just eight years ago will now rush to embrace a man who has offended Mexicans, Muslims and others. The possibility that Trump might actually win fills great swaths of the planet with dread – with the apparent and notable exception of Vladimir Putin’s Russia – with concerns over everything from trade to the nuclear trigger.

While Trump was delivering his speech in Washington, outlining a doctrine of naked self-interest that would “shake the rust off America’s foreign policy”, the heads of all the major UN agencies gathered in Vienna, Austria, for a strategy session with secretary general Ban Ki-moon, now in his last eight months in office.

“Surely he can’t win the nomination,” said a top official in one UN agency before a formal lunch hosted by Ban, only to be told by a colleague that the US political ground was shifting and, yes, Trump was very likely to be the Republican nominee. “Well he certainly won’t win the general election against Hillary [Clinton],” the top official responded decisively. He compared the situation to France over recent decades, where centrists of different stripes came together to block the far-right Front National from winning the presidency.

“People from the centre will stop him. Normal Republicans would rather vote for Hillary. Surely it won’t happen,” the senior official said, and his colleagues nodded.

A European diplomat said the same air of disbelief permeated Brussels. “I think everyone would be utterly incredulous if he did win. No one is expecting it to happen. Call it denial, I suppose.”

He contemplated the prospect of a victorious Trump in November tentatively. “It would be incredibly damaging to transatlantic relations, I suppose, though we would hope that a President Trump would not be quite as extreme as presidential candidate Trump.” Then he banished the thought. “I don’t really think it can happen – do you?”

It was among officials specialising in nuclear diplomacy that anxiety took its most solid form. They had something very concrete at stake, in the shape of an international nuclear deal with Iran concluded in the Austrian capital last July after years of negotiations. Under the agreement, Tehran will abstain from a broad range of nuclear activities and limit others in return for relief from sanctions. Trump has portrayed as it as an Obama authored American capitulation to the Islamic Republic.

“My big concern is that he has said he will tear up the nuclear deal with Iran. That would be catastrophic,” said a senior diplomat in Vienna. “It was the biggest step forward in decades towards peace and stability in the Middle East and in counter-proliferation. The idea that he would just destroy all that, is simply terrifying. It is also deeply concerning in general that he is clearly not a multilateralist. He would be more single-minded in pursuing purely American interests.”

Barack Obama has commented more than once on how he is getting questions “constantly” from foreign leaders about Trump and his proposals. In the UK, “Trump” has become an epithet to be hurled back and forth in the increasingly acerbic battle over the country’s future in the European Union. Boris Johnson, the London mayor and the leading advocate of a British exit from the EU (known as Brexit), has tried to fight off comparisons with the Republican frontrunner for his populist style, bulky frame and unruly mop of hair. But that has only redoubled the determination of his critics to make the parallels stick.

One British diplomat cringed at the idea of both men rising to the top of the political food chain in their respective countries. “Imagine a UK-US summit in the future, with President Trump coming to visit Prime Minister Johnson in a rump Britain, without Scotland, which has left after Brexit,” the diplomat said. “It ought to be unthinkable, but it’s not unthinkable. Not anymore.”



Boris Johnson, the London mayor, has tried to fight off comparisons with Donald Trump. Photograph: Dominic Lipinski/PA

On Wednesday, Trump claimed that Clinton and Obama were to blame for a “reckless, rudderless and aimless foreign policy” in the Middle East. Saudi Arabia is so disenchanted with Obama after his “pivot” to arch rival Iran and his vacillation over Syria that it would welcome almost anyone else in the White House – though Trump certainly gives them pause. On top of his notorious pledge to ban Muslims, the candidate suggested that America would stop buying Saudi oil unless Riyadh provided troops to fight Isis.

“Trump is too polarising,” said one Riyadh analyst, hedging bets on what is evidently an alarming prospect. “But if he does win he will be different. He will be a like a deer caught in the the headlights, surrounded by advisers telling him what to do and he will have to deal with institutions. I don’t think he has a plan.”

While most Israeli officials and senior politicians have been careful to keep their counsel over which of the candidates would be best for Israel in their opinion, recent evidence – not least the increased focus of Israel Hayom, the Sheldon Adelson-owned freesheet and a paper regarded as inseparable from prime minister Binyamin Netanyahu’s own thinking – suggests a swing more behind Trump.

But Michael Oren, a former Israeli ambassador to the US and now a member of the Knesset for a centre-right party, told Channel 1 in a recent interview that Trump “is viewed with a lot of consternation. Israel has grown accustomed to, and deeply appreciates America’s role as leader of the free world … and Israel has a paramount strategic interest in a proactive and a strong America that is going to take a leadership role on a world stage”.

During the election campaign, Trump has repeatedly bashed China, claiming that he respects it but will prove a far tougher negotiator over trade. Earlier this month the Chinese finance minister, Lou Jiwei, called him “an irrational type” due to his proposal that tariffs on imported Chinese goods be increased to up to 45%.



Shen Dingli, the deputy head of Fudan University’s institute of international affairs, described Trump as a “foolish” man who was taking advantage of a “naive America”. But he said he was a foolish man Beijing should welcome in the White House. George W Bush had done huge damage to America’s standing in the world by invading Iraq, Shen argued. A Trump administration would continue that trend.

“Everybody knows that American aggression has made China rise more rapidly. So if another American president would invade Panama, would invade North Korea, would invade Vietnam, that would give China superpower status because America would weaken itself,” Shen predicted, adding: “So [we would be] happy to see it.”

Obama’s work in building bridges in Latin America, symbolised by his recent visit to Cuba, would also be jeopardised. The former president of Brazil, Fernando Henrique Cardoso, told the Guardian a Trump presidency would be bad for Brazil and would push Latin America closer to China.

An old car passes by a house decorated with the flags of the US and Cuba in Havana, ahead of Obama’s visit last month. Photograph: Orlando Barria/EPA

“I see this with great concern,” he said. “It’s a factor of uncertainty in the world. He has not made explicit what he plans to do. And the things that he has made explicit are awful, particularly in relation to Latin America and the Mexicans.”

From the Republican hopeful’s plans to build a wall across the border with Mexico to his belligerency over immigration and Isis, the Brazilian statesman said Trump’s views were bigoted and risky. “I think its dangerous. Just formulating these issues in this way is very dangerous.”

The threat posed by a Trump presidency is not limited to its neighbours. “He has a backwards world view,” Cardoso said. “In sum, not just for Brazil but for the whole world – the election of Trump would be a disaster.”

A Washington-based diplomat from Latin America, who did not wish to be named, said he found the ascent of Trump “worrisome”, explaining: “He’s changed the political landscape, the terms of debate. What was extreme and beyond the pale is now in the media mainstream.”

Warning that Trump would create more enemies in the Middle East, the diplomat added dryly: “He would make an important contribution to anti-American sentiment around the world.”

Trump’s rhetoric has caused particular disquiet in neighbouring Mexico, which has steadfastly stated it would not put a peso toward the billionaire’s proposed border wall. Former president Vicente Fox memorably declared: “I’m not going to pay for that fucking wall! He should pay for it. He’s got the money.”

In March, current president Enrique Peña Nieto lashed out, comparing Trump’s talk to that of fascists in Germany and Italy prior to the second world war. It was a sign the Mexican government was taking a proactive approach on Trump. Peña Nieto appointed a new ambassador to the US and diplomats are promising a pre-election public relations campaign.

On America’s other border, Canada is also watching closely. Tim Barber of Canada 2020, a thinktank with close ties to the country’s governing Liberal party, said: “It’s gone from funny to, wow, this is really scary. We really need the US and the US markets. We’re hugely dependent from a trade perspective.”

If Europeans had a vote, Clinton would win by a landslide: 46% of people polled in seven European countries by YouGov would choose Clinton, compared to only 6% who want to see President Trump sitting in the oval office. Elmar Brok, a veteran German MEP, who chairs the European parliament’s foreign affairs committee, said: “He is not predictable and this unpredictability is a danger. And therefore it is not in the common interest, nor in the interest of the west, that we have President Donald Trump.”

This preference is reflected in the EU institutions. “If we have to deal with a clown like Donald Trump it will seriously affect the relationship between the EU and US,” said one European source. But nobody is losing too much sleep: others said Trump was unelectable, and would be forced to moderate his views in the unlikely event of taking office.

Reacting to Trump’s speech on how he planned to reform America’s foreign policy, Germany’s foreign minister Frank-Walter Steinmeier, said: “I can only hope that the election campaign in the USA does not ignore an appreciation of reality.”



He said that any future US president had to accept that the architecture of global security had changed, and “as such, ‘American First’ is no proper answer to that”.

Nicholas Dungan, a senior adviser at the Paris-based Institut de Relations Internationales et Stratégiques (IRIS) told the Guardian that France was in danger of underestimating Trump.



“First of all nobody can really believe Donald Trump can become president of the United States because he is not at all the sort of American they recognise ... The French relationship with other countries has traditionally been between elites because since the Huguenots until now, there have not been large French populations abroad ... What I have been trying to explain to the French media is that Trump is an authentic American and he represents the face of authentic America and it would be wrong and makes no sense to write him off.”

Central and eastern European leaders may be particularly wary after Trump declared Nato was “obsolete”. Judy Dempsey, senior associate at Carnegie Europe, said: “What Trump has said about Nato is music to the Kremlin’s ears. If that is what an American thinks of Nato, the bedrock about the transatlantic alliance, which Russia is always trying to divide and split and weaken, well, Trump is handing them a silver platter.”



Russian president Vladimir Putin. Photograph: Mikhail Svetlov/Getty Images

Last December Putin called Trump “a very colourful and talented man” and “the absolute leader” in the US presidential race, and since then Russia has remained just about the only place on the planet outside the US where the idea of a Trump presidency is viewed positively. In a YouGov poll of all G20 countries, Russia was the only one where a majority of people backed Trump over Clinton.

In an interview with Izvestia newspaper earlier this week, the top foreign policy official in the Russian parliament, Alexei Pushkov, said Moscow would welcome the “pragmatic” approach of Trump to international affairs.

“He has expressed his willingness to negotiate with the Russian president and not be in conflict with us like the current administration. He looks much less ideologically biased than Obama. He’s a businessman and he looks at everything like a succession of business deals. This isn’t the worst approach, if you compare it with the fundamentalist approach of the Bush and Obama administrations who have destroyed regions and peoples in the name of liberal chimeras and pseudo-values.”

Yury Melnik, press secretary at the Russian embassy in Washington, said: “We see that Donald Trump is one of the few candidates here – current or former – who does not throw punches at Russia. It does not mean we favour him; it’s just an observation that he is different from the pack.”

Trump earned widespread mockery during his foreign policy speech when he mispronounced Tanzania as “Tan-ZAY-nee-uh”, contrary to the country’s actual name, pronounced “Tan-zu-KNEE-uh”. Indeed, Africa has rarely figured in his pronouncements. David Coltart, a former government minister in Zimbabwe, said: “I think that most democrats in Zimbabwe are appalled by some of his statements.

“Ironically I think that some of the more authoritarian figures in Zimbabwe quite admire the stance that he’s taken, but most Zimbabweans would be very worried about the foreign policy that Donald Trump would implement. The last thing we need is an aggressive foreign policy, a trigger happy American president who’s not going to allow the evolution of democratic forces to hold sway.”

Reporting team: Kate Connolly in Berlin, Kim Willsher in Paris, Jennifer Rankin in Brussels, Tom Phillips in Beijing, Jonathan Watts in Rio de Janeiro, Ian Black in London, Ashifa Kassam in Toronto, Shaun Walker in Moscow, Saeed Kamali Dehghan in London, Peter Beaumont in Jerusalem and David Agren in Mexico City.