In a video animation released in December 2017 the Saudi crown prince, Mohammed bin Salman, oversees an invasion of Iran after Iranian boats attack a Saudi humanitarian ship. At the end of the video, Saudi troops storm a military compound where a haggard, trembling Qassem Suleimani, the commander of the Quds force, surrenders on his knees. The video, created by an outfit calling itself Saudi Strike Force, was produced in multiple languages including Mandarin and has been viewed more than 1.5m times.

Clamouring for tough action against Iran, then for de-escalation has characterised the Saudi-Iran rivalry since 1979

In real life, Suleimani is now dead, killed not by the Saudis but in a US strike on 3 January outside Baghdad airport, having just returned from Lebanon and Syria on one of his many missions as the architect of Iran’s regional power base.

Saudis on Twitter were gleeful and official Saudi media were jubilant, declaring in al-Riyadh newspaper that a new decade had started for the region as Iran’s dark shadow receded. If Saudi officials celebrated, they did so quietly, relieved Suleimani was dead, and even more relieved they didn’t have to do it themselves, but wary of Iranian retaliation. There were calls for quick de-escalation, and within three days the crown prince’s brother and deputy minister of defence, Khalid bin Salman, travelled to Washington DC for meetings at the White House.

This pattern of clamouring for tough action against Iran and then calling for de-escalation has characterised the Saudi-Iran rivalry since the Iranian revolution of 1979. That year is remembered mostly as the moment when Iran and the US became enemies in the wake of the US embassy hostage crisis in November. But the relationship between Tehran and Riyadh was also transformed. The two countries, once friendly rivals and pillars of US efforts to contain Soviet influence in the region, became enemies when Ayatollah Ruhollah Khomeini, the ultimate leader of the revolution, began to challenge the Saudis in their role as leaders of the Muslim world and custodians of the two holy sites of Islam, Mecca and Medina.

The rivalry has become an intrinsic part of US-Iran enmity over the past 40 years, creating a threesome in which Saudi Arabia plays the role of indispensable counterweight to Tehran. But Saudi Arabia both thrives off this state of affairs and feeds it. As much as the kingdom fears Iran, its status as America’s special friend in the region has become tied to the continuation of the regime in Tehran.

This explains why Riyadh was so angry with Barack Obama for pursuing detente with Iran, worried it would undermine its own place in the region. This dependence has become even more important at a time when the US-Saudi relationship is fraught with tensions over the alleged hacking of Amazon president Jeff Bezos’s phone by bin Salman and the killing of the Washington Post columnist and Saudi journalist Jamal Khashoggi. All of Saudi Arabia’s faults and excesses seem to be excused as long as the Trump administration is focused on pressuring Iran.

But Saudi Arabia now finds itself with a conundrum. The kingdom wants Iran beaten up but not broken, and it relies on others to do the job because it is not up to the task – not militarily and not from a strategic planning perspective. However, Saudi Arabia has found that the Trump administration may be a fickle friend when it comes to defending the kingdom in case of an Iranian attack, as happened in September 2019, when a suspected Iranian drone struck Saudi oil facilities. The US responded with a lot of heat but little fire: there was no US retaliation on behalf of Saudi Arabia. And though the Trump administration has since deployed thousands of additional troops to the kingdom, the Saudis still felt vulnerable. This is why, within a month of the attack on the Saudi Aramco oil processing facilities, the Saudis were exploring indirect talks with Iran, with the help of Iraq and Pakistan, to try to reduce tensions.

After the killing of Suleimani, the Saudi calls for de-escalation fit the same pattern. Having watched with alarm as Iran expanded its influence in the region over the past few years, thanks in large parts to Suleimani, the kingdom will now be hoping there’s an opportunity for them: no matter how many of Suleimani’s stratagems have been institutionalised, his successor will not be as efficient. Is there room to engage with Shia leaders in Iraq who would like to distance themselves from Iran? Is this the moment to squeeze a compromise out of Hezbollah in Lebanon, Iran’s mostly successful proxy?

The Iranian commander had become the young crown prince’s nemesis, one who in all probability inspired some jealousy and admiration for having achieved what bin Salman felt the kingdom has never quite mastered: a regional strategy that inspires both fear and respect with a solid network of loyal proxies and allies.

The bombast of the 2017 animation, which showcases Saudi Arabia’s extensive and expensive military arsenal, reflects the fantasy that Prince Mohammed indulged in when he first rose to power between 2015 and 2017, trying his hand at an uncharacteristically muscular Saudi foreign policy as he launched wars and embargoes. The video starts with a sentence from an interview that Prince Mohammed gave to the Saudi state television, al-Ekhbariyya, in May 2017 during which he said: “We will not wait until the fight is in Saudi Arabia – we will bring the fight to Iran.”

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By now, the crown prince has been sobered somewhat by the realisation that his swagger has delivered nothing on the regional front except a devastating war in Yemen and a useless embargo on Qatar. Even worse, it was Iran that brought the war to Saudi Arabia with the Aramco attack.

Now that the US is showing its teeth with the killing of Suleimani and more sanctions on Iran, Saudi Arabia may feel reassured, but it cannot be certain whether there is a new, coherent Trump policy or this is a one-off that will leave them exposed again the next time Iran lashes out.

As protests continue in Iran and the Trump administration ramps up pressure on Tehran, choking it economically, talk of regime change or collapse is in the air again. Saudis are also watching with trepidation. At the end of the video animation, Saudi forces are welcomed as saviours in Tehran as citizens wave the Saudi flag – a fantasy if ever there was one. In real life, not only would Saudi troops be unwelcome in Iran, but actually the kingdom needs the current Iranian regime to survive.

• Kim Ghattas is a senior fellow at Carnegie Endowment for International Peace and author of Black Wave