At least eight Revolutionary Guard members have been killed and 20 injured in an attack on a military parade in the Iranian city of Ahvaz.

OPINION: The men who carried out Saturday's attack on the parade in Ahvaz, in Iran's southwestern province of Khuzestan, were well trained: four of them killed 25 people and wounded 70 others before they were shot dead. The question is whether they were trained by Islamic State or by the backers of the low-profile Ahvaz National Resistance, which also claimed credit for the attack.

Islamic State is an independent ultra-extremist Sunni Muslim movement that kills Shias (most Iranians are Shia) on principle, so there are no big political implications if it was IS that planned the attack.

If it was the Ahvaz National Resistance, however, then these were the opening shots in the next Gulf War, because the ANR is backed by Saudi Arabia and its smaller Arab allies like the United Arab Emirates and Bahrain.

SUPPLIED Saudi Arabia's de-facto ruler, Crown Prince Mohammed bin Salman, said last year that "we won't wait for the battle to be in Saudi Arabia. Instead, we will work so that the battle is for them in Iran."

Iran is convinced that it was the latter. "It is absolutely clear to us who committed this crime ... and whom they are linked to," said Iranian President Hassan Rouhani. "The small [Arab] puppet countries in the region are backed by America, and the US is provoking them and giving them the necessary capabilities."

There is reason to suspect that this is true. The Arab countries of the Gulf are smaller and weaker than Iran and have talked themselves into the paranoid conviction that Iran intends to destroy them, perhaps even to replace Sunni with Shia Islam. They talk of war with Iran as inevitable, and dream of drawing America into such a war to even up the odds.

President Donald Trump is also paranoid about Iran, and openly talks about overthrowing the Iranian regime. Indeed, his personal lawyer, Rudolph Giuliani, boasted on Saturday that US sanctions are really hurting Iran: "I don't know when we're going to overthrow them. It could be in a few days, months, a couple of years. But it's going to happen."

AP Civilians try to take shelter in a shooting scene, during a military parade.

So this could be a marriage made in heaven (or somewhere else in the supernatural world, perhaps). But first there has to be a spark, some Iranian action that gives both Trump and the Arab Gulf states a pretext for attacking Iran – for they both think in terms of attacking Iran first, not of defending against a (highly improbable) Iranian attack.

Saudi Arabia's de-facto ruler, Crown Prince Mohammed bin Salman, said last year that "we won't wait for the battle to be in Saudi Arabia. Instead, we will work so that the battle is for them in Iran." If they get their war, both leaders expect that most of the heavy lifting will be done by the US Air Force, but something bad has to happen on the ground first. Iran has to do something stupid.

How do you get it to do something stupid? Well, you could try supporting separatist movements in the various ethnic minority areas that ring the country: Arabs in the southwest, Kurds in the northwest, Turkmen in the northeast and Baloch in the southeast. With luck, the Iranian regime will overreact and massacre enough of the separatists (and innocent bystanders) to provide the pretext for an Arab-US attack.

AP Iranian armed forces members march in a military parade similar to that struck by gunmen on Saturday.

After Saturday's attack in Ahvaz, Dr Abdulkhaleq Abdulla, a prominent United Arab Emirates scholar who tends to say what other people don't dare, tweeted that the attack wasn't really a terrorist incident at all. He pointed out that "moving the battle to the Iranian side is a declared option", and predicted that the number of such attacks "will increase during the next phase.

"If that's the Saudi/American strategy, then sooner or later they will manage to goad the Iranian regime into committing some atrocity in return, and then we're away to the races."

It would the fourth Gulf war in less than 40 years. The first was the 1980-88 Iraq-Iran war, in which the Iraqi dictator Saddam Hussein attacked the new revolutionary regime in Iran with the warm support of the United States. Up to a million people were killed, most of them Iranian, but the only direct US support was to give Saddam's forces intelligence and targeting information for their attacks.

The second was the 1990-91 war between Iraq and most of its Arab neighbours, plus large numbers of American and other Western troops, after Saddam invaded Kuwait.

The third was in 2003, when George W Bush invaded Iraq in the mistaken belief that Saddam had links with the al-Qaeda terrorists who made the 9/11 attacks and/or was working on weapons of mass destruction.

And the fourth, coming soon to a theatre quite a long distance from you, will be the US/Gulf Arab attack on Iran.

Of course, the attack in Ahvaz on Saturday could just have been another meaningless spasm of hatred by Islamic State, and not a Saudi/American initiative at all. But if not now, then soon.

* Gwynne Dyer's new book is 'Growing Pains: The Future of Democracy (and Work)'.