Republican political strategist, foreign policy analyst and former surrogate for Donald Trump’s 2016 and 2024 presidential campaigns.

Let us be clear about what happened on February 28. The United States, in concert with Israel, went to war with Iran. It was not the proxy war of attrition that Washington had tolerated for four decades, not the pinprick retaliatory strikes that have been the preferred narcotic of timid administrations, but real war, with the declared intention of breaking the regime’s military power and ending its nuclear ambitions once and for all.

One hundred days later, the question is not whether this was worth doing. It manifestly was. The question is whether Washington has the fortitude to see it through.

One must consider what has already been achieved, and consider it honestly. Iran’s ballistic missile programme — the crown jewel of its deterrent strategy, the instrument with which it held the entire Middle East hostage — has been largely destroyed. Its navy has been decimated. The nuclear sites at Fordow, Natanz and Isfahan, into which the regime poured decades of effort and tens of billions of dollars, have been reduced to rubble.

Whatever the carping of intelligence bureaucrats with agendas and axes to grind, the International Atomic Energy Agency’s own assessment was unambiguous: the damage was enormous. The radical regime spent a generation building towards developing nuclear weapons. That project is finished. The degrading of Iran’s military will take years to reverse.

And then there is the supreme leader.

For 37 years, Ali Khamenei was the Islamic Republic. He was its theologian, its strategist, its supreme will. He built Hezbollah into a terrorist state within a legitimate state. He sustained Hamas through every Israeli military campaign. He dispatched the Islamic Revolutionary Guard Corps (IRGC) to prop up Syrian dictator Bashar al-Assad, to arm the Houthis, and to establish militias across Iraq.

He kept the hostage-taking, the terrorism and the assassination plots running as instruments of state policy — while Western capitals issued demarches, held conferences and imagined that engagement might moderate him. It did not moderate him. It never was going to moderate him. He is gone now, killed on the first day of a war he spent his life making inevitable.

The critics — and there is no shortage of them, in the faculty lounges and the think tank corridors and the op-ed pages of the familiar publications — insist that regime change has not materialised. They say this as though it settles the argument. It does not.

Totalitarian regimes do not fall on a schedule convenient for their opponents. The Soviet Union did not collapse the morning after US President Ronald Reagan deployed Pershing II missiles in Europe. The process of terminal decline is exactly that — a process.

What we can say with confidence is that the Islamic Republic today bears no resemblance to the Islamic Republic of February 27. Its supreme leader has been liquidated. Dozens of its senior officials are dead. Its IRGC command structure has been gutted. Its economy, already on life support before the first bomb fell, has now suffered $270bn in damage by the regime’s own admission. Its currency is in catastrophic freefall.

The Iranian people cheered in the streets of Tehran when Khamenei died. That is not nothing. That is, in fact, everything — the seed of something that, given time and resolve, will flower into genuine change.

The costs have been real. No serious person denies it. But costs must be weighed against alternatives, and here the critics fall conspicuously silent. What was the alternative? Another decade of nuclear negotiations that Tehran would string along while its centrifuges spun? Another round of sanctions that hurt ordinary Iranians while leaving the IRGC untouched? Another “maximum pressure” campaign that produced maximum Iranian defiance?

The foreign policy establishment that now clucks about oil prices and Pentagon budgets is the same establishment that spent 40 years managing, containing and accommodating a regime that was trying to build a nuclear bomb, directing proxy armies and murdering Americans. Their counsel had a cost too; it just was not itemised on a Pentagon spreadsheet.

The Islamabad ceasefire says everything one needs to know about the actual balance of power in this conflict. Iran did not agree to pause because it was winning. It agreed because it was desperate, because its military had been broken, its economy was bleeding out and it needed time to breathe.

The Strait of Hormuz situation is a nuisance, not a strategic reversal. The naval blockade is costing Tehran $500m a day. The squeeze will intensify. The regime’s capacity to sustain resistance will diminish. Iran’s maximalist demands for reparations are the language of a regime performing defiance for a domestic audience, not the language of a power that believes it holds the cards.

One hundred days ago, the Islamic Republic was the pre-eminent destabilising force in the Middle East, armed with ballistic missiles and a near-nuclear capability and a network of proxies stretching from the Mediterranean to the Gulf. Today, its supreme leader is dead, its arsenal is shattered, its nuclear programme is in ruins, and its treasury is being drained daily by a US naval blockade.

This is what US power looks like when it is actually applied. It is uncomfortable. It is expensive. It is, by any serious strategic measure, an achievement of historic proportions.

The hardest work remains. But those who refuse to acknowledge what has already been accomplished are not being clear-eyed. They are being wilfully blind — and on the question of Iran, wilful blindness has always been the more dangerous indulgence.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.