Israel still has not officially acknowledged that the attack in Iran in the early hours of Friday morning was its doing.

Meanwhile, Iran's military and political leaders have downplayed, dismissed and even mocked that anything of consequence happened at all.

The accounts over what kind of weaponry was deployed on Friday and how much damage was caused are still conflicting and incomplete.

American officials speak of a missile strike, but Iranian officials say the attacks, in the central province of Isfahan and in northwest Tabriz, were caused by small exploding drones.

"The downed micro air vehicles caused no damage and no casualties," Iran's Foreign Minister Hossein Amir-Abdollahian insisted to the semi-official Tasnim News Agency.

But these simple quadcopters are Israel's calling card – it has deployed them time and again in its years of covert operations inside Iran.

This time their main target was the storied central province of Isfahan, which is celebrated for its stunning Islamic heritage.

Of late, however, the province is more famous for the Natanz nuclear facility, the Isfahan Nuclear Technology Centre and a major air base, which was used during Iran's 14 April attack on Israel.

It is also an industrial heartland housing factories which produce the drones and ballistic missiles that were fired by the hundreds in Israel's direction last Sunday.

So a limited operation seems to have carried a powerful warning – that Israel has the intelligence and assets to strike at will at Iran's beating heart.

It is a message so urgent that Israel made sure it was sent before, rather than after, the start of the Jewish Passover, as was widely predicted by Israel watchers.

US officials have also indicated that Israel targeted sites such as Iran's air defence radar system, which protects Natanz. There is still no confirmed account of its success.

So this attack may also be just an opening salvo. But it was, for the moment, an unintended 85th birthday gift to Iran's Supreme Leader, Ayatollah Ali Khamenei.

Israel's official silence gave Iran's ultimate decision-maker vital political space. Tehran did not have to invoke its new rule that whenever its arch-enemy strikes, Iran will hit back hard, with the risk of sparking a perilous escalatory spiral.

Hardline President Ebrahim Raisi did not even mention these most recent events in his Friday speeches.

For the Islamic Republic, it is all about what it dubs Operation True Promise – its unprecedented onslaught against Israel in the dead of night last Sunday. He hailed what he called his country's "steely will".

Iran has prided itself for years on its "strategic patience", its policy of playing a long game rather than retaliating immediately and directly to any provocations.

Now, it is invoking "strategic deterrence". This new doctrine was triggered by the 1 April attack on its diplomatic compound in Damascus, which destroyed its consular annex and killed seven Revolutionary Guards, including its most senior commander in the region.

Iran's supreme leader was under mounting pressure to draw a line as Israel ramped up its targets during the last six months of the grievous Gaza war.

No longer just striking Tehran's assets, including arms caches, buildings, bases and supply routes on battle grounds like Syria and Lebanon, Israel was also assassinating top-ranking officials.

A decades-long hostility, which had previously played out in shadow wars and covert operations, erupted in open confrontation.

Whatever the specifics of this latest tit for tat, there is a more fundamental priority for both sides: deterrence – a more solid certainty that strikes on its own soil will not happen again. If they do, there is a cost to pay, and it will hurt.

For the moment there is an audible sigh of relief in the region, and in capitals far and wide.

Israel's latest move, under anxious urging from its allies to limit its retaliation, will have eased this tension, for now. Everyone wants to stop a catastrophic all-out war. But no one will be in any doubt that any lull may not last.

The region is still on fire.

The Gaza war grinds on, causing a staggering number of Palestinian casualties.

Under pressure from its staunchest allies, Israel has facilitated the delivery of greater quantities of desperately needed aid, but the blighted territory still teeters on the brink of famine.

Israeli hostages have still not come home, and ceasefire talks are stalled. Israel still warns of battles to come in Hamas's last stronghold in Rafah – what aid chiefs and world leaders say would be yet another untold humanitarian disaster.

Iran's network of proxies across the region, what it calls an "Axis of Resistance" stretching from Hezbollah strongholds in Lebanon through Iran-aligned militias in Iraq and Syria, to the Houthis of Yemen, are at the ready, still attacking daily.

In the last few weeks, simultaneously everything and nothing has changed in the region's darkest, most dangerous days.

By Lyse Doucet,Chief international correspondent