The answer to America's foreign policy malaise, he said, could be summed up in two words: Donald Trump.

"We are totally predictable. We tell everything. We’re sending troops, we tell them. We’re sending something else, we have a news conference. We have to be unpredictable."

Trump as a presidential candidate addresses the foreign policy establishment at the Mayflower Hotel in 2016. Credit:Bloomberg

"We must as a nation be more unpredictable," he said.

Reading from a teleprompter and speaking in unusually subdued tones, Trump vowed to end military adventurism in the Middle East, force America's NATO allies to boost their defence spending and develop closer ties with Russia and China.

So he appeared before a crowd of Washington elites at the historic Mayflower Hotel to unfurl his "America First" vision for US foreign policy.

In April 2016 Donald Trump was well on his way to securing enough votes to become the Republican Party's presidential nominee. Massive crowds were attending his raucous rallies, but the celebrity businessman wanted to show a different, more cerebral, side to his candidacy.

Just six months later Trump won the presidential election and set about turning his foreign policy rhetoric into reality.

Instead of laughing, they would have been better off listening.

"Ronald Reagan," Graham said, "must be rolling over in his grave."

"I’m the only one who knows how to fix it".

In November Fred Kempe, chief executive of the Atlantic Council think tank, praised Trump for showing "a refreshing willingness to take on critical issues that his predecessors either avoided altogether or ineffectually kicked down the road".

"Trump’s first two years in office have been marked by a surprising degree of stability," Eliot Cohen, a former senior official in the State Department, wrote in Foreign Affairs. His shortcomings, Cohen wrote, "have not yet translated into obvious disaster".

"Trump’s foreign policies are better than they seem," read the title of a 112-page report released by the Council on Foreign Relations think tank in April.

Trump's election victory mortified the Washington establishment. But at the halfway point of his first term many experts were expressing relief at how it had turned out.

His approach to global affairs has been unconventional and unpredictable, just as he promised.

Trump pulled the US out of the Trans Pacific Partnership trade agreement and the Paris Climate Accord. He shifted the US embassy in Israel from Tel Aviv to Jerusalem.

"America is moving into a more fraught, dangerous period where the margin for error is shrinking," Hal Brands, a professor of global affairs at Johns Hopkins University, wrote this week. "An administration that drives recklessly is running out of road."

There are now increasing doubts about how long this style of policy-making can be sustained.

Richard Haass, the president of the Council on Foreign Relations, says Trump's approach to foreign relations has five key features: hostility to multilateral institutions and alliances; the use of tariffs and sanctions to achieve ambitious, even unrealistic, goals; increased military spending but decreased military action; a reduced emphasis on promoting democracy and human rights, coupled with a penchant for strongmen; and a faith in Trump's personal diplomacy but not in professional diplomats.

"The Trump administration is engaged in a global juggling act involving so many strategically significant balls that it would confound the capabilities of the most skilled circus performer," Kempe wrote this week.

But in recent weeks that sense of relief has been morphing into alarm. The US has found itself entangled in a series of foreign policy conflicts that are growing increasingly tense. From the Middle East to Asia to Latin America, everywhere you look the colossal ambitions of Trump's foreign policy are colliding with reality.

The tweet followed a period of increased tensions between the two rivals, including the US sending warships such as the USS Abraham Lincoln to the Gulf of Oman, and destroyers into the Persian Gulf through the Strait of Hormuz.

There has not, however, been a full-scale war - and that's what Trump appeared to threaten in a tweet on Sunday night: "If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!"

There have been many fraught moments since: when Iranian revolutionaries held 52 American diplomats hostage for 444 days; when the US Navy shot down an Iranian airliner carrying 290 passengers; when George W Bush designated the country part of an "axis of evil".

An Iranian woman holds an effigy of US President Donald Trump during a rally. Credit:AP

The two countries have been fierce enemies since the 1979 revolution that saw the pro-American Shah overthrown and replaced by Supreme Leader Ayatollah Ruhollah Khomeini.

The most serious flashpoint is the relationship between the US and Iran.

"It’s time for the American people to become fully alert to a dreadful possibility," conservative commentator David French wrote in the National Review.

"The United States, led by an erratic chief executive who is frequently ignored even by his closest advisers, may find itself stumbling into its worst war in more than a generation."

Colin Kahl, a former national security advisor to Joe Biden, said the US had found itself in "a very ominous situation - one in which the risk of military confrontation grows by the day".

The Trump administration, Kahl wrote, "is doubling down on a strategy of maximum tension, and there is growing evidence it is on a path toward war - whether Trump realises it or not".

The seeds of the current crisis were planted a year ago when Trump withdrew the US from the Iranian nuclear deal. Known officially as the Joint Comprehensive Plan of Action (JCPOA), it was an arrangement between Iran, the permanent members of the United Nations Security Council (the US, Russia, China, France and Britain), Germany and the European Union.

In exchange for sanctions relief, Iran agreed to eliminate its stockpile of medium-enriched uranium and dramatically reduce its number of gas centrifuges.

The deal was the signature foreign policy achievement of the Obama Administration. But Trump believed it was "defective at its core" because it had not stopped Iran from funding radical terrorist groups or forced it to give up its ballistic missile development.

Several of Trump's top advisers, including secretary of state Rex Tillerson and defence secretary James Mattis, wanted the US to remain in the agreement.

"If we can confirm that Iran is living by the agreement, if we can determine that this is in our best interest, then clearly, we should stay with it," Mattis said.

But last May Trump officially withdrew from the deal and reinstated sanctions on Iran.

The United States, led by an erratic chief executive who is frequently ignored even by his closest advisers, may find itself stumbling into its worst war in more than a generation. David French, conservative commentator

They have had a devastating effect on Iran's economy, which has contracted by 6 per cent this year after falling by 4 per cent in 2018. Unemployment in Iran sits at 12 per cent.

Tillerson and Mattis have since left the Trump administration. Stepping into the void have been two hardline Iran hawks: Secretary of State Mike Pompeo and National Security Adviser John Bolton. Both have played key roles in recent moves to intensify pressure on Iran.

In April Pompeo announced that US was designating Iran’s Islamic Revolutionary Guard Corps a terrorist organisation.

And earlier this month Bolton announced the US had deployed a battleship-carrier strike group as a warning to Iran because the Islamic Republic had engaged in "a number of troubling and escalatory indications and warnings".

Leading Iran hawks in the Trump administration Mike Pompeo and John Bolton. Credit:AP

The administration’s goal, he said, was "to send a clear and unmistakable message to the Iranian regime that any attack on United States interests or on those of our allies will be met with unrelenting force".

Exactly where this is all supposed to lead is unclear.

"My sense is we are not going to transform them into something we're comfortable with and we are not going to be able to overthrow them," Haass says. "I just don't see a serious strategy that's emerged for dealing with Iran."

A nightmare scenario

For leaders in Europe watching the tit-for-tat between the US and Iran, rising tensions or even war in the Middle East is a horrifying prospect. They feel an urgent sense of responsibility not to let it happen.

"In this new situation it’s become a question again: 'Is there going to be a war in this region which would be extremely detrimental to the countries in the region, but also for the EU which is only a stone’s throw away?'” says Amanda Paul, senior policy analyst at the European Policy Centre in Brussels.

"It is all right for the United States, they are on the other side of the world … but for their partners and friends in the region it’s actually a nightmare scenario that we find ourselves in.”

The Age and Sydney Morning Herald spoke to senior Western diplomats in Europe for this story, none of whom wanted to go on the record. Some declined even to be quoted anonymously.

"All the ingredients are there,” one Western diplomat said. "Just one unfortunate event could lead to a conflict which could spill over into other countries. We are very concerned."

Another common term used was "miscalculation". The worst-case scenario, at least in the short term, is not a deliberate act by one side or another, but a mistake that sparks a war.

The EU and individual EU nations are embarking on an intense diplomatic effort to try to keep Iran onside – both directly and through back-channels and regional proxies.

America is moving into a more fraught, dangerous period where the margin for error is shrinking. Hal Brands, professor of global affairs at Johns Hopkins University

And they are also talking to the US, but with little success. It comes down to a fundamental difference of opinion: the US seems to believe that maximum pressure is most likely to force Iran to the table to make new concessions on its nuclear program, but the EU believe they are badly mistaken. Their information is that Iran will not buckle.

There is no question sanctions are having a big effect on Iran’s (rather opaque) economy, with runaway inflation hurting the poor and changing diets. Eggs are much less affordable now, for example.

But the Iranians defiantly embrace their "resistance economy" – a political culture steeped in the idea of self-sacrifice, grounded in a history of survival against opposition and the odds.

The regime is good at keeping the basic safety net intact, and food on tables. And there is little sign of a co-ordinated internal protest. Indeed, sanctions are working in favour of the regime in this respect.

Diplomats have observed that, over the past year, people now ascribe their economic woes to US sanctions, and not without reason.

Pedestrians walk down the street in Tehran, Iran. Credit:Bloomberg

Losing patience

So for the time being the EU and its member countries feel it is up to them to keep Iran onside – and in compliance with the 2015 nuclear deal.

When the US pulled out of the deal, Iran continued to comply with it. But a year on the regime is losing patience. Iran's leadership announced last week that it would resume the production of nuclear centrifuges and begin accumulating nuclear material.

The country's leaders also warned Iran could resume high-level uranium enrichment if the remaining signatories to the deal did not make good on promises to shield its oil and banking sectors from American penalties in the next 60 days.

The subtext of Iran’s 60-day ultimatum is that it is intended as a "hurry up" to Europe, to work harder to show Iran the upside of sticking to the deal.

The next assessment by international inspectors is due at the end of May and the Sydney Morning Herald and The Age understand it will again – as it did the last 14 times – report that Iran is complying with its obligations.

Iranian President Hassan Rouhani. Credit:AP

Though Amanda Paul feels the slow death of the deal is "inevitable" with US sanctions in place, several Western diplomats said they did not believe this. Many expect Iran to tread as close as possible to the line, even put a toe over it, but not just walk over it.

Iran, they believe, has a history of working in grey territory where there is room for diplomacy. And that is why there is still hope.

Not all experts are critical of Trump's approach to Iran.

"Under Obama we were fooling ourselves; Trump is dealing with reality," says Michael Doran, a senior fellow at the Hudson Institute and a senior official in the George W. Bush administration.

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"If we want an Iran that doesn't threaten its neighbours and doesn't have a nuclear weapon we have to confront them. A lot of people who would usually agree with this policy direction can't bring themselves to say that because they can't give Trump credit for anything."

Rather than seeking a confrontation with Iran, he says Trump's aim is to bring them back to the negotiating table.

"Trump got elected on a peace and prosperity platform," Doran says. "He isn't looking for war."

There are also signs Trump is growing frustrated with the advice from hawkish advice from Bolton, a leading proponent of the 2003 Iraq War.

Bolton has played a key role in the administration's tough approach to another global hotspot, Venezuela, which is aimed at driving Nicolas Maduro's socialist government from power. But a failed coup attempt by the US backed opposition leader Juan Guaido earlier this month convinced Trump that Bolton had underestimated Maduro's staying power.

Fire and fury: the sequel

If Trump's tweet threatening "the official end of Iran" looked familiar, that's because it was. In August 2017, he issued a similar threat to North Korea, warning he would rain down "fire and fury" against the nation unless it improved its behaviour.

For a while it looked like Trump's "maximum pressure" approach to North Korea had worked. Kim Jong-un refrained from nuclear testing and the two leaders met at a historic summit in Singapore last June.

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The US and North Korea agreed to work towards the complete denuclearisation of the Korean Peninsula. It was a vague commitment, but it kept hostilities at bay. Trump would later boast at his rallies that he "fell in love" with the North Korean dictator.

But a follow-up summit in Hanoi in February ended in disaster when the talks broke down with no agreement.

Since then there has been no signs of progress and earlier this month, after 522 days without a ballistic missile test, North Korea launched several new short-range ballistic missiles.

It wasn't a nuclear or a long-range missile test, so it didn't breach the terms of any agreement with the US. But it was a sign of a new assertiveness on behalf of the North Koreans.

Then the US seized a North Korean shipping vessel carrying coal exports that was violating American law and international sanctions

North Korea’s ambassador to the United Nations, Kim Song, called the seizure "an outright denial of the underlying spirit" of the June 2018 joint statement between Trump and Kim Jong-un.

"The United States should deliberate and think over the consequences its outrageous acts might have on the future developments," the ambassador said.

And then there's China

Trade negotiations between the US and China, which seemed to be progressing towards a deal, have hit a brick wall.

Trump's senior economic officials accused China earlier this month of reneging on written promises made during negotiations. The US announced that it would raise tariffs on $US200 billion ($290 billion) worth of Chinese goods from 10 to 25 per cent and started the process to apply to tariffs to virtually all goods that enter the US.

Despite a jittery stockmarket, Trump has indicated he is happy to settle in for a long period before any deal is struck.

"Tariffs will make our Country MUCH STRONGER, not weaker," he tweeted recently. "Just sit back and watch!"

The administration also opened up a new front in its economic battle with China by placing telco giant Huawei on a blacklist that bans American companies from buying its equipment.

Chinese President Xi Jinping speaks after he reviewed the Chinese People's Liberation Army Navy fleet in the South China Sea in April last year. Credit:AP

And in the South China Sea, it's persisting with "freedom of navigation" exercises within the 12 nautical mile limits of islands claimed by China prompting claims that the US had "damaged the peace, security and good order" of the area.

In September 2018, a Chinese warship sailed within metres of an American destroyer in the contested waters, forcing it to change course.

If the President starts racking up some wins - a substantial trade deal with China or staring down Iran and forcing some change in their stance - he will have proven his critics wrong. But we're a long way from that, and the global diplomatic atmosphere is getting worse, not better.

With 18 months of his term left, Trump the disrupter has been on full display. He's been able to use American power to inflict significant economic damage on its geopolitical rivals.

But Trump the master deal maker – capable of finding solutions to difficult global problems – is yet to be seen.