The New York Times reports:

Israel was mere moments away from an airstrike on April 1 that killed several senior Iranian commanders at Iran’s embassy complex in Syria when it told the United States what was about to happen.

Israel’s closest ally had just been caught off guard.

Aides quickly alerted Jake Sullivan, President Biden’s national security adviser; Jon Finer, the deputy national security adviser; Brett McGurk, Mr. Biden’s Middle East coordinator; and others, who saw that the strike could have serious consequences, a U.S. official said. Publicly, U.S. officials voiced support for Israel, but privately, they expressed anger that it would take such aggressive action against Iran without consulting Washington.

The Israelis had badly miscalculated, thinking that Iran would not react strongly, according to multiple American officials who were involved in high-level discussions after the attack, a view shared by a senior Israeli official. On Saturday, Iran launched a retaliatory barrage of more than 300 drones and missiles at Israel, an unexpectedly large-scale response, if one that did minimal damage.

The events made clear that the unwritten rules of engagement in the long-simmering conflict between Israel and Iran have changed drastically in recent months, making it harder than ever for each side to gauge the other’s intentions and reactions.

Since the Oct. 7 attack on Israel by Hamas, an Iranian ally, and Israel’s subsequent bombardment of the Gaza Strip, there has been escalation after escalation and miscalculation after miscalculation, raising fears of a retribution cycle that could potentially become an all-out war.

Even after it became clear that Iran would retaliate, U.S. and Israeli officials initially thought the scale of the response would be fairly limited, before scrambling to revise their assessment again and again. Now the focus is on what Israel will do next — and how Iran might respond.

“We are in a situation where basically everybody can claim victory,” said Ali Vaez, the Iran director of the International Crisis Group. “Iran can say that it took revenge, Israel can say it defeated the Iranian attack and the United States can say it successfully deterred Iran and defended Israel.”

But Mr. Vaez said: “If we get into another round of tit for tat, it can easily spiral out of control, not just for Iran and Israel, but for the rest of the region and the entire world.”

This account of these tense weeks is gleaned from interviews with U.S. officials, as well as officials from Israel, Iran and other Middle Eastern states. All of them spoke on the condition of anonymity to discuss sensitive matters they were not authorized to reveal publicly.

Planning for the Israeli strike in Syria started two months earlier, two Israeli officials said. The target was Mohammad Reza Zahedi, the commander for Syria and Lebanon of Iran’s elite Quds Force, a branch of the Islamic Revolutionary Guards Corps.

About a week beforehand, on March 22, the Israeli war cabinet approved the operation, according to internal Israeli defense records that summarized preparations for the strike and were viewed by The New York Times. The Israeli military did not comment on the internal assessment.

Those records also outlined the range of responses from Iran that the Israeli government expected, among them small-scale attacks by proxies and a small-scale attack from Iran. None of the assessments predicted the ferocity of the Iranian response that actually occurred.

From the day of the strike, Iran vowed retaliation, both publicly and through diplomatic channels. But it also sent messages privately that it did not want outright war with Israel — and even less so with the United States — and it waited 12 days to attack.

American officials found themselves in an odd and uncomfortable position: They had been kept in the dark about an important action by a close ally, Israel, even as Iran, a longtime adversary, telegraphed its intentions well in advance. The United States and its allies have spent weeks engaged in intensive diplomacy, trying to tamp down first the expected Iranian counterattack, and now the temptation for Israel to reply in kind.

When it came this past Saturday night, Iran’s show of force was significant, but Israel, the United States and other allies intercepted nearly all of the missiles and drones. The few that reached their targets had little effect. Iranian officials say the attack was designed to inflict limited damage.

U.S. officials have been telling Israeli leaders to see their successful defense as a victory, suggesting that little or no further reply is needed. But despite international calls for de-escalation, Israeli officials argue that Iran’s attack requires yet another response, which Iran says it would answer with still more force, making the situation more volatile.

“The question now is how does Israel respond in a way to prevent Iran from rewriting the rules of the game without provoking a new cycle of state-on-state violence,” said Dana Stroul, a former top Middle East policy official at the Pentagon who is now at the Washington Institute for Near East Policy.

In fact, Israeli leaders came close to ordering widespread strikes in Iran on the night Iran attacked, according to Israeli officials.

Israeli officials say the Oct. 7 attack by Hamas, which caught them by surprise, changed the ground rules of regional conflict. To its enemies, it was Israel’s bombing and invasion of Gaza that did that, and it led to increased rocket fire by Hezbollah, Iran’s proxy in Lebanon. That in turn drew heavy fire from Israel.

The Israeli airstrike in Damascus killed seven Iranian officers, three of them generals, including Mr. Zahedi. In the past, Israel had repeatedly killed Iranian fighters, commanders and nuclear scientists, but no single strike had wiped out so much of Iran’s military leadership.

By March, the relationship between the Biden administration and Israel had grown increasingly fraught, as Washington criticized the Israeli assault in Gaza as needlessly deadly and destructive — “over the top,” as President Biden put it.

Then came the Israeli strike in Damascus. Not only did the Israelis wait until the last minute to give word of it to the United States, but when they did so, it was a relatively low-level notification, U.S. officials said. Nor was there any indication how sensitive the target would be.

The Israelis later acknowledged that they had badly misjudged the consequences of the strike, U.S. officials and an Israeli official said.

Defense Secretary Lloyd J. Austin III complained directly to Israel’s defense minister, Yoav Gallant, in a call on April 3, U.S. officials said, confirming an earlier report by The Washington Post. Mr. Austin said that the attack put U.S. forces in the region at risk, and that the lack of warning had left no time to ratchet up their defenses. Mr. Gallant had no immediate comment. [Continue reading…]