The following is an excerpt from the new book, “In the War Room: The Inside Story of Israel’s Fight Against Hamas and the Iranian Axis,” by Yonah Jeremy Bob and Elliot Kaufman, published by Wicked Son.

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How did Iran’s regime, the master of proxy warfare, come to engage in open fighting with its more powerful adversaries? One answer is its stubborn pursuit of nuclear weapons, the focus of President Trump’s single day of strikes in June 2025’s 12-Day War. But the current war with Iran has been focused as much, if not more, on Iran’s missile program. That is what unleashed the open warfare in the first place.

On April 14, 2024, Israel’s two-front battle with Hamas and Hezbollah exploded into a three-front war. Iran attacked Israel with more than 110 ballistic missiles, dozens of cruise missiles, and some 170 drones. One of the largest single drone and ballistic-missile assaults in military history, this was an act of aggression that permanently altered the Middle East.

Until this point, Tehran and Jerusalem had engaged in a shadow war, one that had been going on for 45 years with little fundamental change. Both sides preferred to kill each other’s operatives and destroy each other’s assets through proxies or clandestine services. This preserved plausible deniability and avoided a direct confrontation that would have unpredictable consequences.

Why did this enduring pattern break down? One reason is that each party became too successful at its own mode of operation. The Islamic Republic achieved “too much” on October 7, 2023, via its junior proxy Hamas. But this Iranian “success” awakened the sleeping Israeli giant, shifting it from the limited retaliations of the past against Hamas to a far more aggressive strategy that sought to overthrow the terrorists running Gaza. Both Gaza City and Khan Yunis, Hamas’ northern and southern capitals, were not merely subdued by the IDF. They were destroyed.

Hezbollah, Iran’s most powerful proxy in its campaign to destroy the Jewish state, had fired rockets, missiles, and mortars at Israel since October 8, 2023. By December, the IDF had started to rout Hezbollah’s forces in southern Lebanon. But in a way, this only increased the frustration among Israel’s leaders that Iran had managed to inflict a two-front war on Israel without suffering any direct consequence. Everyone knew that Hamas and Hezbollah were armed, trained, and funded by Iran to menace Israel. Would the proxy strategy again be allowed to grant Iran immunity?

Not this time, Israel’s war room decided. In December 2023, the Israeli Air Force assassinated Sayyed Razi Mousavi, a senior Islamic Revolutionary Guard Corps commander, in an airstrike near Damascus. Israel increased its attacks on IRGC officials in Syria, a key hub for Iran’s proxy war, until it crossed an Iranian line.

On April 1, 2024, Israel took out Mohammed Reza Zahedi, the top commander in the IRGC’s Quds Force for Lebanon and Syria, in an airstrike on Damascus. Zahedi had also commanded the Quds Force’s Unit 1800, which is responsible for smuggling ammunition and precision weapons into Lebanon. That went to the heart of Hezbollah’s war effort.

Israel had kept silent on its responsibility for such occasional targeted assassinations of Iranians in Syria, and in the past, Iran’s leader Ayatollah Khamenei had used that silence as an excuse not to take direct retaliatory action. This was how the game worked. But the killing of Zahedi, the manager of the Syrian and Lebanese proxy fronts for Iran, went too far for the regime. Khamenei decided that he needed revenge.

Iranian media reported that Zahedi had been meeting with leaders of Palestinian Islamic Jihad, another Iranian terror proxy, at the time of the strike. According to later Israeli accounts — once the IDF eventually admitted to the strike — the Air Force had targeted a building adjacent to the Iranian embassy. But this was not the narrative presented to the world. The world heard that Israel had hit part of the Iranian embassy itself. Some reports at the time indicated that the building had served as the residence for Iran’s ambassador to Damascus and was very close to Canada’s embassy as well.

Herzi Halevi, the IDF chief, privately admitted that the IDF and the Mossad had misjudged the situation. “Netanyahu and the other senior cabinet members throughout the war told me they did not want to accidentally drag Iran into the war,” he confided to other IDF officers.

Sources close to the Mossad sought to distance it from responsibility. “The [IDF] plan for the location of the assassination did not mention anything about the embassy of Iran. The Mossad saw that only afterward. The analytical assessment of potential scenarios could have been different if there had been information connecting it to the Iranian embassy,” one source told us. “This was a fundamental error.”

These intelligence sources focused not on whether the building was diplomatic in the formal sense, but on how the activities it hosted would cause the world to perceive it as diplomatic. Had the Mossad known this beforehand, it likely would have nixed the attack, in its telling.

Halevi was not having it. “After time had passed since the killing” of Gen. Zahedi, he recounted to other officers, “Dadi [Barnea, the Mossad director] said, ‘I don’t know if there were enough dapaot’” — contingencies listed in the pre-strike IDF Intelligence documents. Halevi responded to him, “You supported it, don’t try to wriggle out” of responsibility now.

We can reveal that the Israeli miscalculation was shared across the board and involved an inability to imagine a larger Iranian reaction than a counter-attack against an Israeli embassy. On March 20, 2024, several senior and mid-level IDF and Mossad intelligence officials attended a planning meeting for the targeted strike. Among the Mossad representatives, we can also disclose, were those with analytical responsibility for Iran as well as for Canada, suggesting that the Mossad understood the sensitivity of the target.

We can further disclose that there was a PowerPoint presentation at the meeting which showed that the target location was close to the Iranian and the Canadian embassies, highly sensitive sites, on both sides. Yet at the time, the scenarios offered by the Mossad and the IDF for Iran’s potential reactions to the strike were moderate — and nearly identical.

Offering a rare explanation of the secretly discussed intelligence process, Halevi said the pre-strike contingencies presented by IDF Intelligence and the Mossad included a medium-to-high probability of a proportionate Iranian retaliation. The agencies thought Syria might fire some rockets or drones at Israel. These secret assessments from IDF Intelligence and the Mossad also found a medium-to-low probability of Iran launching drones directly, which Israel could handle.

On March 21, Halevi gave the strike on Zahedi his final approval. On March 22, Netanyahu gave his final approval at a meeting with Halevi and top IDF Intelligence officials as well as Barnea and the Mossad’s top official for analysis. Again, the IDF and Mossad predictions regarding Iran’s response were essentially the same.

But most decisively, on April 1, Barnea attended the first post-strike meeting of senior Israeli defense officials. He told the attendees that the whole world knew the airstrike had taken place close to the Iranian embassy, and that there was already evidence that Iran was trying to pretend this was its official consulate.

The Mossad chief praised the Air Force and IDF Intelligence for an impressive operation, adding that the latest estimate was that Iran’s response would be more dangerous than some of the lowest pre-strike estimates, but still not so high-risk, perhaps attempting to attack an Israeli embassy someplace. Though even that was not likely, Barnea caveated, and it was probably the worst-case scenario, though Israel should be ready for changes.

All of this suggests that the Mossad knew what IDF Intelligence knew and had very similar views about the expected blowback from Iran both before the attack and in its first analysis after the attack. This means the Mossad’s narrative that it did not have the information to properly advise on the issue would come only later.

Halevi insists the IDF gave the Mossad accurate information. “We didn’t say ‘embassy’ because it wasn’t the embassy. Nor was it a consulate. In the land records of Damascus itself, it was not listed as a diplomatic building,” Halevi said. Israeli Defense Minister Yoav Gallant concurred: The building had no flag. Afterward, Halevi said, the Iranians tried to put a flag there, but they knew the truth.

Even so, why did most of the world see it as an Israeli violation of Iranian diplomatic immunity? For one, the building was adjacent to an Iranian diplomatic building. According to Halevi’s version of events, because they were so close by, the Iranians sometimes used the second building, where Israel struck, as surplus office space. Sometimes, the Iranian ambassador had even slept there. Israel’s misunderstanding, sources indicated, was to believe it mattered that the Iranians had ceased sleeping in the building for some time. Tehran and other capitals viewed it as every bit a diplomatic building nevertheless.

For three weeks before the strike, the IDF had tried to clarify which floor and room Zahedi would be in, but it did not succeed. This meant the Air Force needed to use a larger munition. Pressed on why it was necessary to kill such a high-ranking Iranian official in the first place, Halevi explained to other officers that Iran was pushing the Syrians to fire more on Israel directly from Syrian territory, and that Israel wanted to stop the trend. In trying to deter attacks from Syria, then, Israel ended up escalating with Iran directly. But it did not know that at the time.

“After the fact,” Halevi has said, “Iran immediately claimed it was an embassy and told this to the leader, Khamenei,” misleading Iran’s top decision-maker. The IDF chief believes this internal Iranian deception changed everything. Ayatollah Khamenei did not often travel outside his palaces and command centers and relied on a small coterie of advisers to receive updates about the world. Had the ayatollah known that Israel had merely hit overflow rooms from the embassy, rather than the embassy itself, he might not have responded the same way.

If the ayatollah was misinformed, he wasn’t alone. “Some of the top American officials really think it was the embassy and view Iran’s claim as authentic,” another senior IDF official told us. U.S. Secretary of Defense Lloyd Austin was furious at the Israeli strike. In his view, Israel was obfuscating the significance of what it had done. He either did not accept Israel’s story about the building, or he thought Jerusalem was standing on a technicality that ignored what mattered: Iranian diplomats used the building, which meant Israel had broken the rules of the game. Austin told Gallant that the Iranians would now up the ante, and he was right. Khamenei would transform the conflict.

Halevi, however, swears by his finding: “We know it was not a diplomatic building. If it was,” he said, “I would not even have suggested the attack to the cabinet.” To the IDF chief’s regret, however, “fake news succeeded in Iran and in the US.” Iran pressed the theme so hard that most top Biden Administration officials, even in private, have told us they believe Israel struck an Iranian diplomatic compound.

The misinformation given to Khamenei led him to order the first-ever massive direct attack on Israel late on the night of April 13, 2024, and early in the morning of April 14. The decision stunned the Mossad and IDF Intelligence, which in 2025 considered it their second-largest miss of the war, following only October 7, 2023. Indeed, IDF Intelligence chief Aharon Haliva was shown the door later in April 2024 not because of the initial failure of October 7, which he had somehow weathered, but because he also underestimated Khamenei’s response in mid-April. He would remain in office for a few more months, but his fate was sealed.

Iran’s direct attack in April 2024 would provoke a direct Israeli retaliation later that month, targeting air defenses. If the conflict had seemed contained in the aftermath, we now know that could not have been further from the truth. The invisible wall, which had prevented direct military exchanges with Iran for decades, had been broken. Another exchange would follow in October 2024, leaving more Iranian air defenses down and clearing the path for the 12-Day War of June 2025. That war’s extraordinary success, in turn, gave President Trump and Prime Minister Benjamin Netanyahu the confidence to launch a new Iran war on February 28, 2026. The wall was down, and each subsequent decision was made in its wreckage.

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Elliot Kaufman is a Wall Street Journal Editorial Board member and writer, focusing on Israel, Iran, and U.S. foreign policy.

Yonah Jeremy Bob is the senior military correspondent at the Jerusalem Post.

“In the War Room: The Inside Story of Israel’s Fight Against Hamas and the Iranian Axis,” can be purchased on Amazon here.

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Inside Israel’s High-Stakes Fight From October 7 To The Heart Of Tehran