Israel-Gaza briefings: Have Iran-Israel missile strikes changed the Middle East?

But policymakers, analysts and military leaders are still absorbing the extraordinary exchange of fire just days ago between two old adversaries, one that arguably came a small technological failure away from triggering a devastating international conflict.

It is worth considering how close they came to the edge and how deep the abyss that lay before them. This was the first time Iran and Israel had attacked each other directly.

Some analysts say the Iranian attack was the largest combined missile and drone assault ever - bigger than anything Russia has levelled against Ukraine. It was certainly the first external bombardment of Israel since Saddam Hussein's Scud missiles in 1991.

Most of the 300-plus Iranian drones and missiles were shot down or failed en route. But I watched from our office in Jerusalem as the night sky was lit up by Israeli air defences trying to bring down the ballistic missiles flying overhead. All it would have taken is for one GPS guidance system to fail for a missile to land in an urban area at huge civilian cost.

"I don't think people realise how close we were that weekend," one senior Western security official told me. "It could have been a very different story."

Yet some in the West think positives can be drawn from the attack on 13 April and Israel's limited retaliation last week. They argue it was a huge intelligence success to predict the Iranian strike, that the defence of Israel was an outstanding example of allied military cooperation, and that both Iran and Israel learned how to climb down the escalatory ladder.

Let's take the intelligence operation first. I am told the US learned about Iran's plans on the Wednesday morning before the attack on Saturday evening. And crucially, they discovered the scale of Iran's ambition.

"We got wind that Iran's response would be at the top end of expectations," said one high-level Western source. "And that was a bit of a shock. But it helped galvanise the international response."

Crucially, it helped the US persuade some countries in the Gulf to join in Israel's defence, including Jordan and Saudi Arabia. Their fear - once they were aware of the scale of Iran's plans - was the risk of an escalatory regional war if Israel had no choice but to retaliate hard. So a mixture of good intelligence gathering and private Iranian signalling (which the US denies took place) gave Israel and its allies time to prepare.

The roles played by Jordan and Saudi Arabia are still not fully clear. Jordan has admitted shooting down Iranian drones in self-defence to protect its sovereignty. It is understood Jordan also allowed Israeli warplanes some access to its airspace. The Saudis are thought to have provided information to the US and kept an eye on any threat from Iranian-backed armed groups in Yemen.

The key point is it worked. The US, British, French, Jordanian and Saudi militaries showed they could operate together on collective air defence.

"It was an extraordinarily successful tactical operation," said the security source. "The intelligence cued it up, we had sight of the whole area and we worked together. No other group of nations can do that in the world." Some have also argued this could be the start of a new regional alliance against Iran.

To others, though, that is a typical security and military perspective, one that celebrates technological success while missing the bigger political picture. The more pessimistic analysts argue that if Iran wanted to inflict significant damage on Israel, it could have refrained from giving advance warning, broadened its targets, launched a second wave of attacks - or even ordered Hezbollah to mount a large attack from Lebanon.

Emile Hokayem from the International Institute for Strategic Studies think tank said the operation revealed how much Israel had to rely on allies for its defence. He also wondered whether Israel would have enough air defence missiles needed for a higher intensity conflict.

"As we've seen in in the war between Ukraine and Russia, it matters how much of the good stuff you have in stock," he said.

The remains of a ballistic missile near Arad in southern Israel, seen on Friday

Mr Hokayem also dismissed the idea this crisis marked the beginning of a new regional military alliance.

"We're not at the cusp of a new era," he said. "Arab states have cooperated because primarily they want to avoid a regional confrontation. And they want to demonstrate they're good partners to their western allies. It's also simply a matter of national sovereignty. They don't want stuff flying and exploding in their skies."

The second claim by optimists is that Iran and Israel have learned from this experience. They say both countries - for once - communicated their intentions accurately; they realised they could de-escalate without losing face; and they both had a scare that will re-establish mutual deterrence.

Iran may have attacked Israel but it warned allies of its intent and signalled early it was a one-off. Israel showed it could retaliate modestly, targeting air defences in central Iran and using a small attack to signal a bigger capability, namely that it could hit Iran where and when it wanted.

I am told Iran may even have been tipped off about Israel's retaliation. Certainly Iran signalled from a very early stage it did not intend to respond to Israel's counter-attack.

Both sides certainly will have learned military lessons. "The attack probably helped Iran identify the relative strengths and the weaknesses of the Israeli air defence system," said the Institute for the Study of War. Israel and the US will also have a greater understanding of Iran's tactical strategies.

Attack sends message to Iran but Israelis divided over response

The counter-argument is that both Iran and Israel broke a taboo, that direct attack is now an easier option.

In an essay for Foreign Affairs, Afshon Ostovar from the Foreign Policy Research Institute says the scale of Iran's attack shows it is no longer convinced by a policy of restraint.

"The notion that Iran intentionally launched a weak attack does not stand up to scrutiny," he writes. "Iran hoped to land an impressive blow against Israel."

Mr Hokayem challenges the idea Iran and Israel have learned to understand each other. He cites Israel's failure to realise the consequences of its decision to kill several elite Iranian Revolutionary Guards Corps (IRGC) commanders in Iran's consulate in Damascus.

"These two countries don't talk to each other. Instead, they just signal through military posturing and third parties. These things can go badly quite quickly. Wrongly reading the other side's intentions - or risk appetite - is a feature rather than a bug in the relationship."

There is also scepticism either side have re-established deterrence. Amos Harel, defence analyst for the Israeli newspaper Haaretz, said: "The two countries breached the previous rules of the game, with limited costs… the balance of deterrence between the two countries (is) unsettled."

Perhaps the key lesson learned by many in this crisis was just how close the region had come to full scale war.

"It was just a huge relief," one Western diplomat told me. "It could have gone so differently."

-bbc