Just after dark on Saturday in Tehran, the commander of the Revolutionary Guards picked up a phone and issued an order to begin “Operation True Promise” — an unprecedented aerial assault by the Islamic republic on the Jewish state.

After Major General Hossein Salami read out the names of the senior Iranian military officials whose killings, in a suspected Israeli air strike on April 1 in Damascus, the guards were seeking to avenge, he chanted a verse from the Koran.

“Fight them!” he said. “Allah will chastise them at your hands, and He will lay them low and give you victory over them.”

Within minutes, the attack began — a swarm of drones took off on a nearly 2,000km, hours-long flight to Israel, soon to be followed by missiles. It was the first direct confrontation between the two most powerful militaries in the Middle East, arch-rivals entangled in a decades-long shadow war marked by Israeli assassinations and Iran’s sprawling Axis of Resistance, which has brought its proxy militias and Iranian soldiers right to Israel’s border.

With Iran’s assault, soon thwarted by Israel’s sophisticated aerial defences, that conflict burst out of the shadows. In Tehran, some rushed to petrol pumps and grocery stores, and others to Palestine Square, draped in Iranian flags. In Isfahan, people cheered as missiles flew over the grave of Mohammad Reza Zahedi, the general killed in Iran’s diplomatic compound in Damascus by the air strike that Israel has not publicly claimed.

In Washington, US President Joe Biden had already cut short a vacation on Saturday and headed back to the White House, worried that this may just be the first volley in an all-out war between Israel and Iran.

In Israel, where the assault had long been anticipated, Prime Minister Benjamin Netanyahu’s plane, the Wing of Zion, took off for safety from Nevatim air base as the missiles approached. Around the same time, dozens of fighter aircraft and defensive systems were deployed to fend off the attack — not just Israeli, but British, Jordanian and American.

At 8pm local time, neighbours saw Netanyahu’s motorcade speed from the Jerusalem home — reportedly fitted with an anti-missile shelter — of a billionaire friend where the Israeli premier and his wife had spent the Sabbath.

What followed was a social media spectacle, perhaps exactly as Iran intended. Across Iraq, Jordan and Lebanon, a macabre parade of drones lit up the night sky, their lethal payloads cheered on by some, including in Beirut, where ravers at a nightclub paused dancing briefly to watch a projectile streak overhead.

What Tehran was banking on, said Holly Dagres, a senior fellow at the Atlantic Council, was a demonstration of might visible to all.

“In the eyes of the clerical establishment, this mission was a success because they were able to hit Israel directly from Iranian soil [and] demonstrate that [despite] its dated Shah-era fighter jets and air inferiority, it now had command of the sky.”

As the drones began their hours-long journey, Israelis huddled at home, staying close to bomb shelters, and after six months of war in Gaza, a stoic humour kicked in. “First direct flights from Iran to Israel since 1979,” joked one Israeli, referring to the year of the Iranian Revolution.

But the gallows humour masked an existential dread around which Netanyahu has fashioned his own political career over the past decade: that a full-fledged war with Iran was eventually inevitable.

Even now, after Israel escaped almost entirely unscathed from the Iranian assault — a child was injured by shrapnel, a military base was lightly damaged and few of the missiles managed to penetrate Israeli airspace — his response will decide if this remains a single, deadly round of tit-for-tat attacks, or the precursor to the war he has long warned about.

Hours after Salami gave the orders in Tehran, and Israel’s air defences had intercepted 99 per cent of the assault, Iran declared its mission accomplished: “the operation is over”.

Around then, Netanyahu was on the phone to Biden, reportedly being told that Israel’s successful defence was enough of a victory, and that the US would not join in any counter-retaliation.

“The president told the prime minister that Israel really came out far ahead in this exchange,” said a senior US official. “Israel took out the IRGC’s . . . leadership in the Levant [and when] Iran tried to respond, Israel had clearly demonstrated its military superiority.”

Israel has faced barrages of rockets from Hizbollah and Hamas for years, fending them off with its vaunted Iron Dome. The sight of its interceptors chasing threats low over the Tel Aviv skyline are by now a familiar sight.

But this was the first time the Jewish state has been attacked by another country since 1991, when Saddam Hussein fired dozens of Scud missiles at Tel Aviv and Haifa while Iraq was at war with Israel’s closest ally, the US.

Back then, Prime Minister Yitzhak Shamir was persuaded by George W Bush not to retaliate. This time around, Netanyahu may prove less receptive to that argument, given the scale of Iran’s assault; Iran launched more ballistic missiles at Israel in one hour this weekend than Iraq did during weeks of war.

As Biden watched from the Situation Room at the White House, at least 100 ballistic missiles were streaking through the skies, minutes from Israeli territory.

But in the balance, Iran may have given Biden’s argument a small boost. Having telegraphed the assault for two weeks, and having mostly used slow-moving drones that Israel’s air defences could easily track and eliminate, Tehran lowered the possibility of mass casualties.

Those drones, some of which — the Shahed-136 — are similar to those Russia has unleashed in Ukraine, have proven easy to take down. Even Ukraine’s limited air defences have done so. At the same time, said an Israeli official, the swarm of drones was designed to probe Israel’s responses and track the locations and trajectories of its defensive assets.

“They learned a lot about us, and we learned a little about them,” said the official. “It was an education.”

Iran’s missiles were less easily deflected but, given the advance warning, Israel had placed its most sophisticated, multibillion-dollar missile defences on high alert. The Arrow system took out most of the cruise and ballistic missiles, while Israel’s allies picked off the rest.

“The Iranians took into consideration the fact that Israel has a very, very strong, multi-layered, anti-missile system,” said Sima Shine, a former official at Israel’s Mossad intelligence agency with a focus on Iran. “And they probably took into consideration that there will be not too many casualties.”

Shine said the assault was similar to the one Iran launched after the 2020 assassination of the IRGC’s revered Qassem Soleimani on the orders of then US President Donald Trump. Then, as now, Iran telegraphed the assault on US troops in Iraq, giving them notice to take defensive measures that resulted in zero casualties under a televised attack.

“From Iran’s point of view, it was a show — ‘we have the capability. We have all different missiles and drones. We can do it. We prefer not to escalate it into a war,’” said Shine. “The fact that we can sit now and talk about the waiting and seeing and thinking and not retaliating is because there were no casualties.”

Indeed, almost immediately after the attack ended, Israel returned to a regular, if martial, rhythm. Citizens were told they no longer needed to shelter, and by Monday night all restrictions on public gatherings would be lifted countrywide.

But the country was still at war, with Hamas, if not Iran. And in the north, just as they have almost daily for the past six months, Israeli warplanes pounded Hizbollah targets in retaliation for rocket attacks earlier that night.

“We intercepted. We stopped [the attack]. Together we will win,” declared Netanyahu on X, signalling that, while this barrage may be over, Israel’s war was not.