Thread by @Nadav_Eyal

1. The Israel-Iran war: The first day.
We are now about 15 hours after Israel launched what it labels a *preventive strike* against the Islamic Republic of Iran - targeting its nuclear facilities and ballistic missile sites.

Here’s a short recap of what’s happened - and what it means.

First, this is not an *operation*. It’s not a *strike*. Israel is now **at war** with Iran. And Israel’s defense establishment understands that well.

I spoke a short while ago with a senior Israeli security official. His most important message was directed at the Israeli public:
"Prepare for Iran’s response, don't underestimate what they can do. It will be substantial and lethal".

2. Now to the war. At the beginning of 2024, while Israel was still fighting the beginning of the war in Gaza, it began receiving what security officials described as troubling signals: Iran was advancing in what’s known as the *weapons group* -the part of its nuclear program focused on the actual assembly of a nuclear bomb or warhead.

I heard details related to attempts by Iran to acquire specific equipment that would only be needed for a timed nuclear detonation. A senior Israeli security official confirmed to me that these signals were captured by Israeli intelligence. This quickly became a major headline - in Israeli newspapers, and then in the international press.

It was during that same period that the IDF’s operations branch began serious planning for a possible strike on Iran’s military, the Revolutionary Guard, and most importantly, its nuclear facilities.

What was obvious to the Israelis was that striking Iran’s nuclear sites could never be done without factoring in the Iranian response to that - which would be substantial, and likely devastating for Israel.

3. The Iranians were very encouraged by their latest missile attack on Israel in later October 2024, and they thought it proved that Israel's Arrow and other defenses have limited capacity to hold off a major barrage. Considering how small Israel is, definitely compared to Iran, they focused on building abilities to bigger strikes, seeing this a soft spot of the Israeli society.
The Islamic Republic had already crossed a major line during the Gaza war – it decided to directly attack Israel not in response to an Israeli action against Iran itself, but rather after two specific events: First, the assassination of a senior Iranian general in a building adjacent to the Iranian embassy in Damascus. Second, an Israeli strike targeting Hezbollah leader Hassan Nasrallah.

To Israeli officials, Iran’s decision to launch missiles and drones at Israel marked a crossing of the Rubicon - a shift from proxy warfare to direct military engagement. Tehran had made itself a party to the war. This strengthened the resolve to act.

4. Another development during the war: Israel obtained, say senior officials, intelligence material revealing a joint plan by Hamas, Hezbollah, and Iranian elements - a plan that wasn’t just rhetoric, but described in detail the actual destruction of the State of Israel. I have seen parts of these documents and some were made public.

What Israel saw- through documents and other sources- was that within the Iranian leadership, the idea of physically destroying Israel as a functioning polity wasn’t just a slogan chanted in mosques.

It was an operational vision: a combined invasion, missile strikes, and internal collapse. A plan they intended to implement. When Israel began planning its strike against Iran, the IDF’s Operations Branch - led by General Oded Basiuk- had to think long and hard. How do you launch such an attack when you know Iran still possesses around 2,000 ballistic missiles, a massive fleet of drones (many of which we've seen used in Ukraine), and fully intends to retaliate in a devastating way -targeting Israeli bases, and possibly its energy and infrastructure?

One of the core ideas that emerged, partly inspired by the operational success against Hezbollah, was this: **Israel’s first strike must be devastating**, not only against the nuclear infrastructure, but against the entire command chain of the Islamic Republic’s military and Revolutionary Guard. It wasn’t enough to just hit the nuclear sites. You also had to eliminate the air defense systems, to ensure Israeli planes wouldn’t be shot down.

It wasn't enough to hit those too - you had to target the **ground-based ballistic missile systems**, which are still capable of launching large, high-impact warheads. In other words: you had to do it *more or less simultaneously*. The problem, of course, is that Israel doesn't have the operational capacity to act simultaneously on multiple fronts like the United States. It doesn’t have B-2 bombers. It doesn’t have enough refueling jets.

5. So Israel had to develop a plan that would maximize its air force's capabilities- prioritizing targets, using every aircraft efficiently, and getting the most out of its limited resources and implementing some new ideas. But even before that – it needed to prioritize, and try to understand what will the Iranian army do, when it understands the attack is under way.

One piece of intelligence led to the Israelis knowing where the Iranian Airforce generals will convene in such a scenario, and how much time they’ll stay there. So they met to decide their response tonight – and were all killed.

But over all of this was one key question: Would the Americans allow it? And let me be clear - Without a green light from the U.S., none of this would have happened.

6. Planning is one thing. Executing is something else entirely. A strike like this requires American coordination—over Middle East airspace, over shared intelligence, over ammunition supply chains. And crucially: what happens if and when Iran retaliates.

These conversations began during the Biden administration. And it was quietly signaled by some U.S. officials that helping Israel in a strike on Iran - or even carrying one out themselves- was not entirely off the table, given what Washington also knew about Iran's nuclear activity.

To be clear: Iran never issued an official order to "break out" for a nuclear bomb. But the fact that Iran seemed to be advancing not just to the threshold in terms of uranium enrichment, but also toward **bomb assembly**, set off alarm bells in Israel- especially after October 7th.

7. That’s something Hassan Nasrallah, Yahya Sinwar, and likely even Iran’s Supreme Leader failed to grasp: Something fundamental changed in Israel after October 7th.

There is now zero tolerance-among both the public and the leadership- for regimes, leaders, or terrorist organizations that speak one the record about destroying Israel, and make actual plans.

The prevailing consensus inside Israel is this: These threats must be confronted directly, and as aggressively as necessary- to ensure that nothing like October 7th, or anything worse, ever happens again. Over the past year, the IDF Intelligence Branch, the Israeli Air Force, and the Operations Division of the General Staff worked together to build a complete picture of Iran’s nuclear program.

But their mission was broader. The element of surprise was part of the plan - but Israeli officials understood that it could never be absolute. The U.S. needed to be notified. The Americans had to make their own regional preparations - like those publicly announced by President Trump and the State Department days earlier, including the evacuation of non-essential diplomats. So the goal became to maintain surprise where possible, without compromising coordination with the U.S.

8. Ahead of the strike, Israel employed a sophisticated psychological deception campaign aimed at the Iranian leadership.

With U.S. assistance, they planted the idea that nothing could happen before the next and supposedly crucial round of talks in Oman - between U.S. envoy Steve Whitkoff and Iranian representatives. This was deliberate misdirection. The Israelis fed that belief, leading Tehran to think that nothing would happen before Sunday. That window-of false security-was essential to the strike plan, because it allowed Israel to **target senior Iranian military commanders who did not go into any alerty** with maximum effect.

That leads to another tactical insight: Israel borrowed a method from its operations against Hezbollah—specifically the systematic targeting of leadership. The thinking was: Eliminating key military leaders diminishes both operational capacity and morale. That’s what Israel attempted last night by killing the Chief of Staff of the Iranian Army, the head of the Revolutionary Guard, and the entire command center of Iran’s Air Force.

This worked to a surprising extent. For example, The Iranians had missiles loaded on launchers, ready to be fired. But after Israel decapitated much of their chain of command, there was **no one left to give the order**. And during that critical delay, Israel used the time to destroy those very launchers.

9. The Mossad also played a role. While not as central as the Air Force or Military Intelligence, it maintained a drone base inside Iran, flying UAVs during the operation. In addition, it deployed equipment that targeted and destroyed anti-aircraft radar systems. Together these elements created a shockwave through the Islamic Republic’s military- a pivotal moment in Iran’s history since the revolution.

But this is not over. Israel did not eliminate the Islamic Republic’s ability to retaliate. As I said at the outset, Israel expects a harsh - and possibly prolonged- response from Iran.

10. Now comes the strategic phase. It’s obvious that the U.S. and Israel are playing **good cop, bad cop** with Iran. Israel strikes. Meanwhile, President Trump says, “I’m ready to sign a deal.”

It’s the same model Israel proposed regarding Hezbollah: The U.S. pushed for a deal *before* the war. Israel said - let us first weaken their capabilities. Then we can talk. Now, Israel is using the same logic with Iran. All wars end. This one will too.

And the thinking in Jerusalem is: if we can cripple Iran’s capabilities first - and then negotiate - that’s the optimal outcome. But for that to happen, the U.S. must stay in the game. It must maintain leverage - either by escalating directly or by continuing to enable and defend Israel’s actions against Iran.

The way this ends matters most – not the first strike. The Islamic Republic fought the Iran-Iraq war for 8 years, and stopped only when its leader, Khumeini, decided its essential for the future of the regime.

If this is to have long-term meaning for the Middle East - if it’s to restore security and stability - then it must also ensure that Iran doesn’t use this war as cover to break out for a nuclear weapon.

No senior Israeli intelligence or military figure believes Iran is incapable of doing so -even in the face of overwhelming Israeli success. What Israel has begun can only be successfully brought to an end by the United States.