With his decision to strike Iran’s key nuclear sites on Saturday evening, Donald Trump could forever change US foreign policy. The two states had their rough exchanges in the past, but have never faced each other in a protracted direct confrontation. It is now up to Ali Khamenei, Iran’s Supreme Leader, to decide what the next phase of this conflict will look like, and for the US to decide on whether to keep responding militarily in the next round. The long-term prospect, however, looks like a strategic disaster.

The US military operation may be a tactical success for Israel, but that does not mean it is a strategic victory against Iran. Militarily, the success was not as spectacular as Trump claimed. Iran’s three key nuclear sites have been clearly damaged by the missiles, which included two of those bunker buster bombs which only the US has and which were never previously deployed. But Iran reportedly moved 400kg of uranium stockpiles elsewhere before the strikes. Vice President JD Vance acknowledged that the stockpile is still intact, but insists that Iran no longer has the capacity to turn it into nuclear weapons.

Iran may respond lightly. It could attack a US base and warn the White House beforehand, thereby keeping diplomatic channels open. Conversely, Khamenei could choose to escalate. The regime is facing an existential threat from Israel and Mossad, which is operating inside Iran to instigate a change of leadership. In this scenario, the regime could decide to go on a suicide mission. It could use its remaining missile stockpiles and activate its proxies in attacks on multiple targets globally. Closing the Strait of Hormuz, as backed by the country’s parliament yesterday, could cripple global trade, possibly bringing China into the conflict. Indeed, US Secretary of State Marco Rubio has already asked Beijing to intervene if Tehran attempts to close the waterway.

Regime change is not an official American objective — yet. But with the help of Mossad, events inside Iran could eventually lead to a change of government. If Israel and the US jointly assassinate Khamenei, it is likely that Iran would remain an enemy of the West, whoever comes into power afterwards. Who, then, would take over? Will President Masoud Pezeshkian or the military be ready to lead this vast country? Without an orderly transition, chaos and new militias are likely to emerge.

So far, US interests are not fully aligned with Israel on regime change and something may have to give. Benjamin Netanyahu may have a short-term interest in a weakened and unstable Iran, but it does not guarantee Israel’s long-term security if it produces more armed militias which cannot be controlled.

Geopolitically, the US strikes have also opened new uncertainties. Iran’s foreign minister has travelled to Russia to hold talks with Tehran’s strategic ally. Iran may explicitly call for Russian assistance, as Moscow has used Tehran’s drones in its war in Ukraine.

America’s strikes on Iran will only make nuclear capability more appealing for Tehran. This is true both under Khamenei’s regime or the nationalist military rule that is likely to follow. Immediate US and Israeli success could be dwarfed by long-term violent instability in the Middle East and shifting geopolitical alliances.

This is an edited version of an article originally published in the Eurointelligence newsletter.