Even as Trump was rage-tweeting on Jan 4, two days after the killing of Iran's top military leader Qassem Soleimani, that he would hit 52 targets including Iranian heritage sites for potential retaliation if America suffered losses following an Iranian attack, warning that "those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD", the US president was busy, secretly using an encrypted back-channel to bring the world back from the brink of war.

As the WSJ reports, just hours after the U.S. strike which killed Iranian Maj. Gen. Qassem Soleimani, the Trump administration sent an urgent back channel message to Tehran: "Don’t escalate." The encrypted fax message was sent via the Swiss Embassy in Iran, one of the few means of direct, confidential communication between the two sides, U.S. officials told the WSJ. Then, in frantic attempts to de-escalate even as top US and Iranian leaders were stirring patriotic sentiment and nationalistic fervor, the White House and Iranian leaders exchanged further messages in the days that followed, which officials in both countries described as far more measured than the fiery rhetoric traded publicly by politicians.

The Swiss ambassador to Iran, Markus Leitner, here with Iranian President Hassan Rouhani in 2017, helped shuttle messages between the U.S. and Iran. Photo: Swiss embassy.

It worked: a week later, and after a retaliatory, if highly theatrical, Iranian missile attack on two military bases hosting American troops that purposefully inflicted no casualties, Washington and Tehran have stepped back from the brink of open hostilities (for now).

"We don’t communicate with the Iranians that much, but when we do the Swiss have played a critical role to convey messages and avoid miscalculation," a senior U.S. official said.

While a spokesman at Iran’s mission to the United Nations declined to comment on the exchanges, he said "we appreciate [the Swiss] for any efforts they make to provide an efficient channel to exchange letters when and if necessary." Another Iranian official said the back channel provided a welcome bridge, when all others had been burned: "In the desert, even a drop of water matters."

In retrospect, it should hardly be a surprise that the perpetually neutral Swiss were the last recourse to prevent potential war.

As the WSJ notes, from the Swiss Embassy, a Shah-era mansion overlooking Tehran, the country’s role as a diplomatic intermediary has stretched through four turbulent decades and seven presidencies, from the hostage crisis under Jimmy Carter to Barack Obama’s nuclear deal. But it was seldom tested like this.

Here's how it happened.

The first American fax was sent immediately after Washington confirmed the death of Soleimani, the most important figure in Iran’s Islamic Revolutionary Guard Corps, the U.S. officials said. It arrived on a special encrypted fax machine in a sealed room of the Swiss mission - the most enduring, and secret, method since the 1979 Islamic Revolution - for the White House to exchange messages with Iran’s top leadership, especially when the two nations are concurrently parading in public media in their bellicose propaganda to earn political brownie points.

The equipment operates on a secure Swiss government network linking its Tehran embassy to the Foreign Ministry in Bern and its embassy in Washington, say Swiss diplomats. Only the most senior officials have the key cards needed to use the equipment.

Early on Friday morning, just hours after Soleimani's death, Swiss Ambassador Markus Leitner, a 53-year-old career diplomat, delivered the American message by hand to Iranian Foreign Minister Javad Zarif. Predictably, Zarif responded to the U.S. missive with anger, according to a WSJ source: "[U.S. Secretary of State Mike] Pompeo is a bully,” he said, according to one U.S. official briefed on Zarif’s response. “The U.S. is the cause of all the problems."

The US may indeed be the cause of all the problems, but it also has all the weapons, and despite the pompous rhetoric, Iran knew full well it could not hope to escalte in tit-for-tat fashion without risking virtually everything. Which is why, Iran was quick to take advantage of Leitner's mediation.

The Swiss ambassador - who regularly visits Washington for closed-door sessions with Pentagon, State Department and intelligence officials eager to tap his knowledge about Iran’s opaque and fluid politics - spent the next several days after Soleimani’s killing shuttling back and forth in a low-key but high-wire diplomatic mission designed to let each side speak candidly. It was a vivid contrast to the jabs of President Trump and Mr. Zarif on Twitter.

Shortly after Trump tweeted on Jan 4 that the US had picked 52 Iranian targets for eventual escalation, Zarif responded just as belligerently on the next day: "A reminder to those hallucinating about emulating ISIS war crimes by targeting our cultural heritage," he wrote. "Through MILLENNIA of history, barbarians have come and ravaged our cities, razed our monuments and burnt our libraries. Where are they now? We’re still here, & standing tall."

However, at the same time as Zarif was seeking to emulate Trump's twitter bluster, the Iranian foreign minister called the Swiss ambassador to take a message to the U.S. It was more restrained, and subsequent statements from both sides helped prevent miscalculations, the officials said.

“When tensions with Iran were high, the Swiss played a useful and reliable role that both sides appreciated,” said a senior Trump administration official. "Their system is like a light that never turns off." Unlike Twitter, that is, which has emerged a medium for spreading premeditated, fake, outrage to mass consumption and whose sole purpose is to distract from what is truly happening behind the scenes.

It's not the first time the Swiss have helped pull back the middle east from the brink of mushroom clouds: they have served as messengers between Washington and Tehran since 1980, in the wake of the seizure of the American Embassy—and 52 hostages —in Tehran by Iranian revolutionaries. Swiss diplomats call the role the “brieftrager” or “the postman.”

In the years after the U.S.-led invasion of Iraq in 2003, the Swiss shepherded messages to help avoid direct clashes. When President Obama assumed office, Switzerland hosted the talks that led to a nuclear deal. When Washington lifted sanctions, Swiss businesses had an early jump on rivals. When Trump reimposed sanctions, he gave the Swiss a phone number to pass the Iranians, saying: “I’d like to see them call me.”

So far, Tehran has continued to speak through the Swiss.

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Why has this archaic method of communication proven so effective at pulling the world back from the edge of crisis?

Former Swiss ambassadors say the diplomatic channel is effective because the U.S. and Iran can trust a message will remain confidential, be delivered quickly, and will reach only its intended recipients. Statements passed on the back channel are always precisely phrased, diplomatic, and free of emotion, something which is clearly impossible on Trump's favorite social media platform, twitter, which he uses for precisely the opposite purpose: to spark outrage and to appeal to base emotions of his core supporter group.

Switzerland, a landlocked country of nine million with no standing army where everyone owns a gun, parlays its role as the world's neutral "postman" (and until recently, secret banker) to lever access to the great powers.

And speaking of Swiss bank, the WSJ notes that currently Swiss diplomats are working to get Washington’s green light for Swiss banks to finance exports to Iran that aren’t subject to sanctions—like food and medicine. "We do things for the world community, and it’s good," said a former ambassador. “But it is also good for our interests." Of course it is: for the privilege of funding the most basic human needs, those same Swiss banks can charge exorbitant rates of interest in a country that for years has had a negative official interest rate.

Iran isn’t the only geopolitical hot spot where the Swiss Embassy represents U.S. or other countries’ interests after the breakdown of diplomatic relations: the Swiss now holds six mandates including representing Iran in Saudi Arabia, Georgia in Russia and Turkey in Libya and the U.S. in Cuba according to the WSJ. In April 2019, the Trump administration asked Bern to represent it in Venezuela but President Nicolás Maduro’s government has yet to approve.

And so, if the world has any hope of avoiding an all out war between US and Iran, it will have to go through Bern, at least figuratively. As tensions between Washington and Tehran have escalated, the Swiss backchannel has remained active. In December the two countries released prisoners at the same time at a special hangar in the Zurich airport - U.S. special envoy on Iran Brian Hook and Iran’s Zarif sat in separate rooms as the Swiss directed the carefully choreographed exchange.

"The Swiss channel has become enormously important because of what they can do in the short term to lessen tensions,” said former New Mexico Gov. Bill Richardson, who worked with the Swiss on the prisoner exchange. “It’s the only viable channel right now."