The element of surprise and the harrowing death toll have inevitably led to comparisons between Hamas's blood-soaked offensive and 9/11 in New York. 

In fact, Al Qaeda then posed no risk of starting a world war and Bin Laden had no plans what to do after his atrocity.

In contrast, Hamas's indiscriminate attack on Israel could well change the world order.

As has been reported, Hamas is bankrolled by Iran. The terror group's weaponry, including the missiles that rained down on Israel at the weekend, were designed and paid for by Tehran.

Ayatollahs have very specific aims in employing Hamas against Israel. 

A key goal is to undo the thawing of relations between the Jewish state and other Middle Eastern nations — Saudi Arabia, the United Arab Emirates, Bahrain, Morocco and Sudan — that occurred between September 2020 and January 2021 with the signing of the Abraham Accords during the Presidency of Donald Trump (who, in contrast to his fiery, war-mongering image, was actually an advocate of peace and co-operation in the Middle East).

Tehran loathes this reconciliatory process. The ayatollahs deny that the State of Israel has any right to exist, and insist it should be wiped off the face of the Earth. Any peace process ending Israel's isolation would push Iran further into the cold.

Provoking Israel also enables Hamas and Iran to stir up sympathy for the Palestinian cause across the Middle East. 

Elsewhere, Iran will now benefit (as, too, will Russia) from the inevitable surge in oil prices as the dangers of a wider Middle Eastern war rise. Meanwhile, the Western economies, already stuttering, face a 1973-style oil-price shock which could cause rifts as each country tries to save its own industry.

Then there are the military implications of this conflict.

An emboldened Iran will extend the export of its missile and drone technology, which is already playing an important role for Russia in its campaign against Ukraine.

Indeed Moscow, though it has had good relations with Israel, has much to gain from a new Middle Eastern conflict.

The U.S. is likely to feel pressure to strengthen Israel's defences against Hamas rockets with weapons like the highly effective Patriot surface-to-air anti-missile system. 

America does not have a big stockpile of these Patriots, and Israel will receive priority, meaning there will be far fewer for President Zelensky's government.

So Moscow and Tehran stand to gain plenty from a long conflict which draws in Israel's neighbours.

For us in the West, things will be much worse than they were after the Yom Kippur War exactly half a century ago, which generated the 1973 shock. 

Our national grid is already having difficulty coping with high demand, but we could be heading back to power cuts and the three-day week.

Then, Britain was the basket case, but tomorrow a hike in oil prices could cause mayhem across a fragile global economy.

Above all it would be the West — Europe, America and Japan — who will take the economic hit, not Russia or China.

Just at a time when the West needs resolution from the very top, the White House's elderly incumbent is a figure whose mental faculties and grasp of policy fail to inspire any confidence.

The sense of weakness that President Joe Biden exudes was embodied in his ludicrously unbalanced deal with Tehran last month, in which the U.S. paid a ransom of $6 billion in return for the release of just five prisoners held in Iran. 

It equalled a direct incentive to hostage-taking, which might explain why Hamas has taken to this tactic in its most recent assault.

American distraction in the Middle East will also be welcomed by China and North Korea, who will feel that they have greater scope to fulfil their territorial and nuclear ambitions in the Pacific.

Amid a deepening Cold War in the Far East, China has adopted a stance of escalating menace towards Taiwan and even the Philippines, and such threats will only be encouraged by the deployment of the biggest American aircraft carrier, the USS Gerald Ford, to the Eastern Mediterranean to bolster Israel this week.

At the same time, the North Korean dictatorship, which already has strong military relations with Tehran, could use the current atmosphere of turmoil to threaten Japan or South Korea.

Suspicions that Kim Jong Un and the ayatollahs have shared nuclear know-how for years could now to turn to Pyongyang slipping a weapon of mass destruction or two to Iran. That would spark a crisis of Armageddon proportions with Israel and the West.

And if this wasn't enough, the fallout from Hamas's attack could re-ignite the tinderbox of civil war in Syria. 

President Assad's government has been moving soldiers to the Israeli border, leaving space for ISIS to re-emerge.

Meanwhile Turkey, a strong supporter of Hamas, feels increasingly emboldened to launch an assault on the restive Kurds there. 

Next door in Lebanon, the powerful Shiite Islamist group Hezbollah might decide to use its vast Iran-supplied missile arsenal against Israel to show its 'solidarity' with Palestine.

Might there be a time, once this has played out, when we look back on the post-9/11 world order with nostalgia?

The prophecy of the great Irish poet W.B. Yeats seems all too appropriate as circles of crisis overlap and worsen each other.

'Things fall apart, the centre cannot hold. Mere anarchy is loosed upon the world.'

Mark Almond is Director of the Crisis Research Institute, Oxford