Beneath Israel’s bombs lies an unpopular and repressive Iranian regime that has spent billions of dollars on a nuclear program and on projecting the Islamic Revolution through armed regional proxies, while presiding over a domestic economic disaster and stifling paralysis.

An 86-year-old autocrat, Ayatollah Ali Khamenei, rules this restive nation, as he has for 36 years, in his role as guardian of the revolution, a conservative calling at which he has proved adept. The supreme leader is no gambler. But his system, remote from a youthful and aspirational society, looks sclerotic to many, and he is now up against the wall.

Over six days of fighting, Israel has struck the Natanz enrichment facility where a majority of Iran’s nuclear fuel is produced, killed at least 11 of the regime’s top generals and several nuclear scientists, bombed oil-and-energy facilities, taken complete control of Iranian air space, and sent tens of thousands of people into flight from Tehran.

At least 224 people had been killed across Iran as of Sunday, a majority of them civilians, a spokesman for Iran’s ministry of health said. But the figure was sure to have grown as Israel’s bombardment continued in the days since. Iranian missiles have killed at least 24 Israelis.

“The Islamic Republic is a rotten tooth waiting to be plucked, like the Soviet Union in its latter years,” said Karim Sadjadpour, an Iran expert at the Carnegie Endowment for International Peace in Washington. “Khamenei is in the most difficult situation he has ever faced.”

The ayatollah has faced threats to his rule before, though, and come out with his supremacy intact. In 2009, when millions of people took to the streets of Tehran to protest what was seen as a stolen presidential election, I watched as state-licensed thugs repeatedly beat brave women demanding dignity and freedom. For a few days, the future of the regime stood on a knife-edge. But with utter ruthlessness it prevailed. Many demonstrators were dragged off to be tortured, sodomized, and in the case of several hundred of them, killed.

Whether the current difficulty facing Iran’s regime will lead to its demise remains to be seen. Isolated cries of “Death to Khamenei” rise into the night sky, but popular protests are impossible under bombs, and always risky under the thumb of the government. There are no obvious leaders to steer any political transition for the same reason.

Ayatollah Khamenei remains defiant. He responded on Wednesday to President Trump’s threat to his life and call for “unconditional surrender” by saying that “Iran stands firm in the face of imposed war, just as it will stand firm against imposed peace, and it will not yield to any imposition.”

These were words typical of a proud nation that rose against the West almost a half-century ago through Ayatollah Ruhollah Khomeini’s revolution, deposing the Shah and imposing “Death to America” as its weekly refrain.

But the insurrection never delivered the freedom it had promised. Frustration, whether over hijabs imposed on women with no desire to wear them or over chronic and crippling mismanagement, grew.

Iran’s gross domestic product, or total output, has fallen 45 percent since 2012, and many people are desperate. Crippling international sanctions over the nuclear program contributed to this downward spiral, but so did corruption, a bungled privatization program and bloated state companies. Iran did reach a nuclear agreement with the United States in the last years of the Obama administration, but Mr. Trump shredded it in his first term.

“The one message the Iranian people wants to get across is that having done all this and wreaked this kind of havoc, make sure the end of this is that the horrendous regime is gone,” said an Iranian businessman based in the United Arab Emirates, who requested anonymity because of the Islamic Republic’s habit of imprisoning its opponents.

At the same time, as the Israeli bombing persists, there are signs of a patriotic surge even among opponents of the regime who have spent time in prison. For some, Iran’s now demonstrated vulnerability is proof of its need for a nuclear bomb, like North Korea’s, to protect itself. In Iran’s neighborhood, Pakistan, India, Russia and Israel all have nuclear warheads.

“Even if we are part of the opposition, we cannot remain indifferent to an invasion of our homeland,” Saddagh Zibakalm, a political science professor who notably refused to trample on U.S. and Israeli flags at a Mashhad university in 2016, wrote in an Iranian newspaper. “We cannot stay silent, or worse, support the aggressor.”

When Israel bombed the headquarters of Iran’s state-owned broadcaster on Monday, causing the anchor in a black chador to cut short her screed against “the aggressor’s assault on the nation’s soil” and “on justice and truth,” the reaction was mixed.

Some Iranians were overjoyed to see a woman in attire many Iranian women reject scurry for cover as the widely detested source of the Islamic Republic’s relentless propaganda was shut down with a loud boom. Others felt torn.

“Damn you Israel! I can’t believe I’m writing in support of the state broadcaster,” Hossein Dehbashi, an author and historian who was sentenced to six months in prison in 2022 for claiming that Ayatollah Khomeini’s son died of a drug overdose, wrote on social media.

It was probably inevitable — given that a clear majority of Iran’s population of 92 million oppose the mullahs’ regime, in the estimation of Mr. Sadjadpour and other observers — that Israel’s six-day-old military campaign would broaden in scope.

The bombing, as Benjamin Netanyahu, the Israeli prime minister, described it, began as a “pre-emptive action” to stop Iran using its enriched uranium to race for a bomb. But that limited mission already seems to have been superseded by something broader.

It always begged a core question: What would stop the regime, if it survived, from spinning the centrifuges and returning to enrichment? Although the nuclear program has never delivered a bomb, and only scant energy at astronomical cost, it has been the mullahs’ most potent nationalist symbol, much like the nationalization of Iran’s oil industry in 1951. This enraged the British, whose oil companies were affected, and led to a coup orchestrated by the C.I.A. and British intelligence in 1953.

There are deep historical reasons, the coup among them, for Iran’s extreme sensitivity to foreign intervention, just as there are deep roots to its quest for liberty through some form of representative government, which began in 1905 with an uprising against the Qajar dynasty, driven by the demand for a constitution.

Now Mr. Trump speaks of “an end, a real end, not a cease-fire, a real end” and Mr. Netanyahu has made little secret of his ultimate objective. “We have indications that senior leaders in Iran are already packing their bags,” he said. “They sense what’s coming.”

There is no evidence, however, that those leaders who are still alive have packed their bags, and how the Israeli bombardment might end in the burial of the Islamic Republic is unclear.

Of course, chaos could ensue from the Islamic Republic’s overthrow. The recent history, in Iraq in 2003 and Libya in 2011, of despots removed through Western military intervention amounts to a cautionary tale.

President Vladimir V. Putin of Russia would no doubt point relentlessly to Western hypocrisy over his war in Ukraine if Israel and the United States use force to topple the regime in Iran.

Already Western powers, even those like France and Germany that usually move in lock step, are split over how to proceed. Friedrich Merz, the German chancellor, said on Tuesday, “This is the dirty work Israel is doing for all of us.”

Speaking to the German ZDF broadcaster, he added that “this mullah regime has brought death and destruction to the world” and “I can hardly imagine the mullah regime returning to its old functions.”

President Emmanuel Macron of France struck a far more cautious note. “I think that the biggest error today would be to seek to change the regime in Iran by military means,” he said on Tuesday. “Because that would mean chaos.”

It would be foolish to underestimate the Islamic Republic’s determination to survive and the lengths it might go to in pursuit of that.

“The Islamic Republic is humiliated and not in a place it’s ever been before,” said Vali Nasr, a former dean of the Johns Hopkins School of Advanced International Studies. “But it could still stay alive long enough to exhaust Israel and get the United States entangled in something it does not want.”

One thing is certain: If the United States does get involved in the war, it will never be forgotten in Tehran. American intervention will become part of a deep American-Iranian psychosis. Its elements already include an anti-democratic coup in Iran by American agents, an anti-Western Iranian theocratic revolution, the U.S. hostage crisis from 1979 to 1981, the American shooting down in 1988 of Iran Air flight 655 with 290 people aboard, and an ideological war that has persisted since the Iranian Revolution in 1979.

That is a lot of bitter history, but one of history’s lessons is that nightmares do end. Almost nobody predicted the fall of the Berlin Wall in 1989. “The Islamic Republic is a zombie regime,” Mr. Sadjadpour said. “It’s fed off and spread disorder for a long time, but it’s terminally ill even if it’s still standing.”

Parin Behrooz contributed reporting.