What makes a successful revolution? The answer is harder than it seems. For a revolution to succeed, it needs to make things better for people than before. But most revolutions are disastrous. If revolutionaries fail, they leave a legacy of destruction and mistrust. If they win, they create new destruction and mistrust. In both cases, there is no end to oppression — which is often the war cry of the revolutionary elite. Misery simply returns in a different mask. There is not a single example to the contrary in the history of the modern Arab state system. From Bakr Sidqi in 1936 through Rashid Ali Al-Gailani in 1941 and Husni Al-Zaim in 1949 to the Free Officers in Egypt, the destruction of the monarchy in Iraq, the bloody return of the Ba’ath in both Iraq and Syria, Libya in 1969 or Sudan a generation later, every military coup led to violent repression, sinister surveillance, economic incompetence and loss of liberty. These were not political but violently coercive systems, where politics was at best a charade. And many people remember with regret what they lost. My older Iraqi friends look back with nostalgia to the monarchical period before 1958. Older Egyptians remember when the Wafd, Young Egypt or the Sa’adists under the monarchy actually meant something politically, in their shared struggle against British colonial control. For younger people, the Arab Spring promised to make politics meaningful again, but ended in the same way. Disappointed hopes and dashed dreams.There are only three revolutions in the modern Middle East that succeeded in building and then sustaining a new political dispensation — and none were Arab: Mustafa Kemal Ataturk’s abolition of the Ottoman caliphate in 1924, Reza Shah Pahlavi’s overthrow of the Qajars in 1925 and Ayatollah Khomeini’s expulsion of Reza Shah’s son in 1979. Both Ataturk and the Pahlavis did good things, modernizing education, agriculture and the economy and increasing social freedoms. Ataturk’s Turkey survives: It was built on solid foundations. Pahlavi’s Iran does not. And now it looks as if its successor, the Islamic Republic of Iran, which Khomeini declared to be a light to the nations, the champion of the suffering masses and a beacon of righteousness, has come to the end of its own tether.The sustained protests inside Iran, about which I have written before, show no signs of dying down. They are not confined to one class, one ethnicity, one gender or one region. They cover the country from the Kurdish northwest to the Baloch southeast. Not everyone has joined in, of course. There have been flickers in the bazaars (as we currently see) and among oil workers, but not so far the sustained strikes we saw in 1978. People are worried, as they always are, about their families, their livelihoods, their futures. But young people in particular are angry. They are also fearless — or perhaps more accurately they have managed to overcome their fear. And they are fed up with a country that promises them nothing but isolation, the grim grind of survival, no fun and continuous surveillance in the interests of — what exactly? The promise of a savior at the end of time or the privileges of a hypocritical elite, who have enriched themselves and their children (as anyone can see through their vainglorious postings on social media) while preaching a purist virtue in which fewer and fewer Iranians actually believe? Many of the brightest and best — maybe 3 million since 1979 — have voted with their feet and left. But most people cannot and probably do not want to. Why should they? The country, after all, belongs as much to them as to the old men of the Guidance Council or the grim-faced thugs of the Basij and the Revolutionary Guard, who threaten them with arrest, torture anddeath for daring to demand the right to choose. The regime seems rattled. It has not been able to suppress the protests this time as easily as it has in the past. As I write, it has reportedly killed more than 500 of its own citizens, including 70 children and 29 women, and arrested 19,000 others, including one of Iran’s most prominent actresses. It has charged 36 people with capital crimes, already sentenced a handful to death in sham trials, executed several — after savage torture — and promised to execute many more. When Iran’s footballers in Qatar failed during their first match at the World Cup to sing the national anthem (itself a curious thing for an Islamist regime to have), it made sure they sang it during the next match. It has intimidated other sports stars and entertainers who have sought to speak out. But this time it cannot intimidate everyone. It has tried to claim that the problem is Kurdish separatism, Daesh or the hidden hand of the US and Israel. Schoolchildren have mocked the claims. It has fired missiles into northern Iraq to try to provoke Kurdish opposition movements into a violent response that might justify its actions. It has failed — at least so far. Leaked recordings of internal discussions, intelligence analysis and public criticism from members of Supreme Leader Ali Khamenei’s own family, plus former President Mohammed Khatami and other senior figures, suggest the regime is now not simply puzzled but also uncertain. Recent reports that it mightliberalize the law on female head coverings and withdraw the Gasht-e Ershad — the so-called morality police — from the streets seem to be misinformation, deliberate or not. Khamenei cannot afford to back down on this central pillar of the regime’s legitimacy, though he may be willing to use promises that he can later break in order to divide the opposition. And the protesters are indeed not unified. This has been a feature of popular protests over the last decade in the wider region. Protests are often deliberately decentered to avoid leaders becoming an easy target. That makes it hard to see how the protesters can move to the next level — which is to offer a convincing alternative to the present system, however awful it might be. This — plus the regime’s record of brutal repression and a widespread and reasonable fear of civil conflict — suggests that the overthrow of that system is still a very long way off. Iranians who want something better — and that is almost certainly a large majority — know they are not alone. Many have lost their fear. When young men in the streets are tipping the turbans off the heads of clerics, you also know that they have lost respect for their clerical rulers. And these rulers have lost what legitimacy they still had in the eyes of many Iranians. Still, this is not 1978 — even if the 40-day cycle of funeral, mourning, funeral, mourning can seem similar. Khamenei is not leaving, as the shah left. And the regime’s praetorian security forces are larger, more indoctrinated and more vicious than anything at the shah’s disposal. They are a minority. But they are armed and brutal. They also feel that they have succeeded in expanding Iran’s power across the region at the expense of its enemies. They have accelerated their nuclear enrichment activities. They just need to keep the home front quiet. That is becoming more difficult.The real crux will come when the Islamic Republic is forced to choose a successor to Khamenei. If that successor can promise genuine change for the better, no one will want revolution. If he can only promise more repression, something will have to give. As an Iranian friend recently remarked to me, the ship of state remains afloat but fatigue has set in. There is little that outsiders can do to shape events. This is something Iranians themselves must do. But we need to ensure that we pay attention. Too often we watch fascinated as protests erupt and then, within weeks, we move on to other things. What happens inside Iran will dictate the future of the region more than anything else. We need to keep sustained pressure on the regime. The nuclear file is doubtless important. But more important is stopping Iran’s ability to undermine and control its neighbors. We need constantly to highlight the regime’s crimes in international forums: Kicking Iran off the UN"s Commission on the Status of Women and commissioning a UN fact-finding investigation into human rights abuses is a good start. But we need more. We should target the regime’s aggressive cyber and surveillance capabilities and respond in kind. Where we can, we should close down its overseas propaganda institutions. We should not host its apologists. We need to say explicitly that we would welcome anything that made Iran a more normal nation.And we need to ensure we pay attention to what Iranians themselves tell us — both inside and outside the country — and not be seduced by those interest groups that pose as reformers but act as Khamenei’s stooges. This will be a game that goes into extra time. We need to make sure we are match fit. Sir John Jenkins is a senior fellow at Policy Exchange. Until December 2017, he was corresponding director (Middle East) at the International Institute for Strategic Studies, based in Manama, Bahrain, and was a senior fellow at Yale University’s Jackson Institute for Global Affairs. He was the British ambassador to Saudi Arabia until January 2015.