On November 21, 1979, Pakistani protesters stormed the United States embassy in Islamabad. They smashed windows and set fire to the building. By the time the Pakistani military had quelled the violence, the embassy had sustained extensive damage and several people — both Americans and Pakistanis — had died.

The attack came at a tense moment for US-Pakistan relations. Several months earlier, Washington had cut aid to Islamabad over concerns about a new Pakistani uranium enrichment facility.

It came at an even tenser moment for Washington’s relations with Tehran. Iran’s Islamic revolution had played out over the previous months, with the pro-US monarchy having been overthrown and replaced by Ayatollah Khomeini. Two weeks before the assault on the US embassy in Islamabad, Iranian radicals had seized the American embassy in Tehran.

In fact, the attack on the American facility in Pakistan was triggered in part by a radio message broadcast by Khomeini in which he falsely claimed that the US was behind an assault on the Grand Mosque in Mecca that had taken place the day before.

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The siege of the US embassy in Pakistan represented the most explosive moment for the US-Iran-Pakistan triangle — one that over the last 40 years has been marked by a hostile US-Iran relationship, a US-Pakistan partnership that has vacillated between cordial and confrontational and a delicate Iran-Pakistan relationship that has played out in the shadow of a Saudi state that is the former’s bitter rival and the latter’s close ally.

A big question for this volatile triangle today is what Washington’s increasingly hard line on Iran might mean for Pakistan — and particularly as Prime Minister Imran Khan, through some strikingly pro-Iran messaging and a key recent visit to Tehran, has telegraphed a desire to take a more explicitly neutral position in the Saudi-Iranian regional rivalry.

The answer underscores just how counterproductive an aggressive US position on Iran can be: American pressure on Iran undoubtedly disadvantages Islamabad — but it also imperils Washington’s own interests, as well as those of its closest friends in the broader region.

In reality, it’s hard to identify any country that benefits from relentless US efforts to tighten the screws on Iran, particularly if the two sides find themselves on a collision course that leads to a military confrontation.

For Pakistan, deepening US-Iran tensions and the risk of confrontation make all the more challenging Islamabad’s efforts to maintain a position of studied neutrality in the Iran-Saudi Arabia dispute. Riyadh — already enjoying some new leverage after its recent $3 billion gift to Pakistan — could pressure Islamabad to side with the Saudis in an unfolding US-Iran crisis.

Washington’s hardline Iran policy also poses problems for Pakistan’s energy security. The US sanctions regime hampers the ability of Pakistan, a nation badly in need of foreign energy resources, to acquire hydrocarbons from a top global supplier (nearly 90 per cent of Pakistan’s energy needs are currently met by imported crude and petroleum products from the Middle East).

And Washington’s tough sanctions on Tehran essentially ensure that the much-hyped Iran-Pakistan gas pipeline remains dead in the water.

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And then there is America. Aside from providing an excuse for US Iran hawks to engage in some chest thumping, it’s hard to imagine an increasingly hardline Iran policy producing positive results for Washington.

Indeed, the worst-case scenario — the American use of force against Iran — would destabilise a Mideast region that has long been a powder keg and a source of concern for US policymakers. Even outcomes short of war, such as sky-high bilateral tensions and repeated US threats, spell trouble for American interests.

Here, consider the war in Afghanistan. Longstanding ill will in US-Iran relations has meant that Washington can’t consider using Iranian territory as part of an alternate supply route to convey Nato materiel to and from Afghanistan, should the current route in Pakistan be closed down — as it was during the serious crisis in US-Pakistan relations in 2011 and 2012.

Instead, Washington would have to depend on alternate routes through Central Asia, which are not only more circuitous and expensive than the Pakistani one, but also vulnerable to the machinations of Moscow. Nato’s Russian rival could try to hamper access to those alternate routes located in what it regards as its sphere of influence.

Additionally, US pressure on Iran raises the possibility that Tehran could retaliate by providing episodic arms support to the Taliban — assistance that US and Afghan officials suspect has already been provided, particularly during the insurgents’ offensive in the western Afghan province of Farah, bordering Iran, last year.

Afghanistan, therefore, also suffers from Washington’s tough Iran policy. And so does India, the other top US partner in South Asia. The Iran sanctions regime hurts New Delhi’s energy interests, which look to Iran as a key partner, and its efforts to develop the Chabahar port project in southern Iran.

Meanwhile, Iran’s Gulf neighbours, including Saudi Arabia, could suffer highly deleterious effects from a continued US-Iran confrontation — none more so than regional destabilisation (though to be sure, any higher global oil prices that result from a fresh Mideast conflagration would be a boon for these energy-producing states).

As for Israel, arguably America’s most critical ally, if Iran were to be hit by US firepower, Israeli territory could well be one of the first targets of Iran-sponsored reprisals.

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And yet, even with so many different countries affected by US-Iran tensions, Pakistan finds itself in a uniquely vulnerable position.

Islamabad has significant relationships with Iran’s US and Saudi rivals. It features a Shia population that according to the academic Vali Nasr exceeds 30 million (the largest number of Shias outside Iran). And it shares a border with Iran, so a potential US-Iran conflict could have direct spillover effects for Pakistan.

In the coming weeks, if US-Iran relations continue to deteriorate, Pakistan could find itself under increasing pressure from both Riyadh and Washington to distance itself from Tehran.

Fortunately for Pakistan, there are two pieces of good news here. First, history shows that Islamabad has successfully managed to withstand pressure from both partners.

Pakistan never formally took a side in the Iran-Iraq war, despite Washington’s preference for it to be firmly in the Iraq camp. And in more recent years, Islamabad resisted Saudi Arabia’s attempt to drag it into Riyadh’s war in Yemen.

Second, President Trump’s tendency to resort to sudden about-faces means that a march towards war is by no means assured. He hinted in recent days that he may be receptive to negotiations with Tehran.

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Still, this much is true: US policy towards Iran isn’t about to magically become more conciliatory anytime soon — including after Trump has left office.

Much ink has been spilled about all the anti-Pakistan feeling in Washington. And yet, the US capital’s deep and often bipartisan hostility towards Iran makes its sentiment towards Pakistan seem jolly by comparison. Perhaps it’s because of the Iranian revolution, the serious threat that US policymakers think Iran poses to Israel, or their belief that Tehran sponsors and stages acts of instability.

Indeed, there are striking similarities between how many in Washington view Tehran and Islamabad: they are both perceived as destabilising players that use militant proxies to cause problems for US interests and American friends.

At any rate, whatever the reasons may be, Washington’s hostility towards Iran is real and relentless. In this regard, President Barack Obama’s bold move in 2015 to extend an olive branch and work with other world powers to conclude a nuclear deal with Tehran should be seen as an anomaly, not a new precedent, for US policy.

Consequently, Pakistan — and the rest of the world — may be spared a conflict between the United States and Iran. But this toxic and confrontational relationship, and the challenges it poses for Pakistan and the world, is likely to endure for quite some time.

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