Defiant rhetoric and obstreperous threats aside, Iran can’t go on like this.

On Tuesday night in the suburbs of Beirut, the IDF killed Fuad Shukr, stage name al-Hajj Mohsin.

A member of Hezbollah’s Jihad Council, Shukr was best known for planning an infamous attack on US military personnel in Lebanon four decades ago. 220 Marines were killed on October 23, 1983, when a suicide bomber struck a barracks in Beirut. It was among the deadliest days for the US Marine Corps since World War II.

Tensions between Israel and Hezbollah reached a boiling point in recent days after an errant Hezbollah rocket slammed into a soccer field in Majdal Shams. The death toll in the Golan Heights community included a dozen children, all Druze Arabs.

Hezbollah denied responsibility for the horrific tragedy, but there was no disputing the origin of the rocket. As I wrote in a Sunday email, the group surely didn’t mean to kill 12 adolescent Arabs kicking around a soccer ball, but intent was irrelevant. Israel had to respond. And they did. IDF fighter jets closed Shukr’s curtain at around 7:40 PM local time on Tuesday.

The strike was yet another reminder that — for lack of a more sophisticated way to put it — Israel knows where these people are. All of them. Including, one imagines, Hassan Nasrallah, who counted Shukr in his inner circle.

Shukr’s death conjured the January strike on Saleh al-Arouri, Hamas’s de facto envoy to Hezbollah. Shukr was killed right up the street from the site of the strike that targeted Al-Arouri.

Again, the losses are piling up for Tehran. In addition to al-Arouri and now Shukr, Iran and its proxies have lost at least half a dozen key commanders and facilitators including arms trafficker Seyed Razi Mousavi, Al-Nujaba commander Mushtaq Taleb al-Saidi, Quds operative Sadegh Omidzade, Kataib Hezbollah underboss Abu Bakr Al-Saadi and Mohamad Reza Zahedi, the highest-ranking Iranian official killed since Qassem Soleimani’s assassination in January of 2020.

Zahedi’s death, in a brazen strike on Iran’s embassy in Damascus, pushed Iran and Israel to the brink of state-on-state conflict in April. Earlier this month, Israel tried, for at least the eighth time, to kill Mohammed Deif, Hamas’s number two. His fate remains unclear.

As I’m always keen to remind readers, these guys aren’t readily replaceable. They’re not random jihadists. Westerners don’t generally understand the distinction, but there’s a difference between Iran’s “Axis of Resistance” and the kind of causeless lunatics who fall in with Wahhabi fanatics harboring delusions of the end times.

Iran’s proxies are well organized, well trained and purpose driven. To kill a commander or a facilitator is to leave a void. In many — but not all, as I don’t want to overstate the case — instances, these men define their positions. Once someone like Saleh al-Arouri’s gone, that role ceases to exist. The same with Mousavi. In simple terms: Iran’s network belongs in business textbooks next to the term “key man risk.”

That’s the context for Shukr’s demise. I’ve said again and again since October that if Hezbollah continues to push the issue — and certainly if there’s another war between Hezbollah and Israel — Hassan Nasrallah’s a dead man. Israel intimated on Tuesday evening that this doesn’t have to go any further. That the ball’s in Hezbollah’s court.

The strike came just as Iran inaugurated new president Masoud Pezeshkian, a self-described reformer who won the race to replace Ebrahim Raisi. Raisi, you’ll kindly recall, flew into the side of a mountain in May, upending Khamenei succession bets. In attendance for the festitivies in Iran: Ismail Haniyeh, Hamas’s political chief, Mohammed Abdulsalam, a Houthi representative and Nasrallah deputy Naim Qassem.