Initially that revolution was quite scary for Iran's Arab neighbours, because its example in overthrowing the local pro-Western ruler and taking a stronger stand against Israel was popular in the Arab street. The solution was to paint Iran as a crazy terrorist state and isolate it as much as possible from the rest of the region.
The other tactic that the conservative Arab states deployed was to stress the religious gulf between Iran (which is 90 per cent Shia) and the Arab countries (whose people are at least 85 per cent Sunni). The doctrinal differences are real, but they do not normally make ordinary people see one another as natural enemies.
Those measures worked for 20 years, assisted by stupid Iranian actions such as holding US embassy personnel hostage for 444 days, but by the end of the 20th century they were losing credibility. What saved the "quarantine" policy in 2002 was the discovery Tehran had been working on nuclear weapons design.
The work was a revival of research that had been started during the US-backed Iraqi invasion of Iran in 1980-88 (when Saddam Hussein certainly was working on nuclear weapons) and was shut down later. It was restarted in 1998, almost certainly in response to the nuclear weapons tests by Pakistan. It was Iran being stupid again, but it was probably never about Israel.
The alleged Iranian nuclear threat provided the basis for another decade and more of political quarantine and trade embargoes that have crippled Iran economically and isolated it politically. All that came to a sudden end last week with the agreement in principle in Lausanne (unless the Saudi Arabian and Israeli lobbies in Washington manage to torpedo it in the next few months).
Iran has about the same population and GDP as Egypt, the biggest Arab country by far, but it is far closer to the Arab Gulf states and to the Sunni-Shia battlegrounds in Iraq and Syria (whose governments are closely linked to Tehran). That's what Sisi was really talking about when he spoke of an existential threat to Arab existence and identity. However, he's still talking through his hat.
Arab existence and identity are nowhere at risk and Iran has no need to paint the Sunni Arab countries as enemies. The Iranian regime may be losing its support among the young (or not), but it has no need to inoculate them against the attraction of Arab political systems and foreign policies by promoting an Arab-Iranian confrontation. They hold no attraction for young Iranians.
As for the notion the Houthi militia that now controls most of Yemen is an Iranian tool (which is the main justification for the military intervention), it is nonsense. The Houthis, like the Iranians, are Shias, but they have their own local interests to protect, and Iran has no plausible reason to want a strategic foothold in Yemen. It is a safe bet that there is not even a single armed Iranian in Yemen.
If the US could send troops into Iraq in 2003 in the delusionary belief Saddam Hussein had weapons of mass destruction, then Saudi Arabia can believe it is fighting Iranians in Yemen now. No country has a monopoly on stupidity, and Riyadh will probably have ample opportunity to regret its mistake.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries