The problem is that Israel alone cannot destroy Iran’s nuclear programme. What’s more, destroying the programme isn’t nearly so simple as bombing a bunch of nuclear plants and research facilities. Iran learned the lesson from Israel’s attacks on Iraq’s Osirak reactor in 1981 and Syria’s Dair Alzour reactor in 2007. Tehran has distributed its nuclear programme widely across the country. It has also buried significant portions of it deep underground. To destroy Iran’s nuclear capability in its entirety, Israel would need to conduct a multi-day air campaign targeting a very large number of sites. It would also need to simultaneously destroy significant parts of Iran’s air defence network and air force.

Even then, Israel wouldn’t be able to secure success. It would also need to deploy ground forces to physically breach and destroy the underground nuclear facilities at Natanz and Fordow. US military sources I’ve spoken to have expressed doubt that even latest-generation US bunker buster munitions (which Israel does not possess) could destroy these facilities with certainty. But getting a commando force deep inside Iran, deep into varied facilities, blowing them up, then exfiltrating would require airlift and close air support capabilities that Israel lacks. It would also require airfield seizures through which to exfiltrate the commandos.

It’s one thing blowing up Hezbollah pagers and bunkers; it’s a very different thing operating at vast scale and depth against a very large defensive force primarily orientated towards defending the very thing Israel would be attacking.

Israel knows this. Which is why successive Israeli governments have put significant pressure on successive US administrations to outline conditions under which the US might join Israeli strikes. But that leads to the extended consideration here: what would happen if Israel did attack Iran’s nuclear programme?

The answer to that question underlines why the last few US presidents have been so deeply hesitant to entertain strikes in that vein. It’s because they know that doing so would invite a full-scale regional war. Khamenei and those at the regime’s ideological power centre regard the nuclear programme both as the guarantee for and destiny of their Islamic Revolution. They would view an Israeli attack on this destiny through a joined political-theological lens of existential threat.

Already paranoid following Israel’s devastation of Hezbollah and intelligence penetration of the Islamic Revolutionary Guard Corps, they would lash out wildly, feeling they had nothing left to lose. They would attempt to strangle trade flows through the Strait of Hormuz, unleash terrorist and missile attacks at US and Israeli bases around the world, and would generally fight hard in the hope that they could bloody Israel and the US enough to win a salvation ceasefire. This is why the US has traditionally reserved its military option for the event in which Iran attempted to actually build and deploy a nuclear weapon.

Again, however, the top line concern is that absent the US military’s support, Israel cannot destroy Iran’s nuclear programme. So the ensuing chaos of any Israeli attack would serve little purpose beyond the thin possibility it might lead to war — and perhaps regime change — in Iran.