Felestin Square, in the heart of Tehran, pulses with life. This area of the country has witnessed events that shaped the fates of empires. During the Achaemenid Empire, trade routes wove through it, connecting the great cities of Persepolis and Susa to the vast expanse of ancient Persia. Thousands of years later, just steps from this square, student revolutionaries seized 53 American hostages, at the dawn of the 1979 Islamic Revolution, which ushered in a new chapter of global upheaval.

Today, there is a clock in the centre of the square, counting down to Israel’s prophesied destruction on 9 September 2040. This countdown is a reminder of the regime’s ambitions, but a far more consequential timer is also in motion—how long will it be until Iran develops a nuclear weapon? Decades of international sanctions and covert sabotage have slowed progress, but not stopped it. Enriched uranium stockpiles and advanced centrifuges have brought Tehran alarmingly close to nuclear breakout capability. At the beginning of December 2024, the International Atomic Energy Agency (IAEA) reported that Iran plans on “dramatically increasing” uranium enrichment. This will “[increase] the capacity to move more quickly to multiple bombs’ worth of weapons-grade uranium,” said Kelsey Davenport, director of non-proliferation policy at the Arms Control Association advocacy group. While more work is needed in terms of weaponisation and delivery systems, the program is inching closer to completion.

If—or when—Iran acquires a nuclear weapon, that will significantly upgrade the country’s strategic position. It could make the regime “immortal,” in the words of Benjamin Netanyahu. It’s unlikely—though terrifyingly possible—that Iran would use those nuclear weapons. That would be genocide, suicide, and quite possibly usher in the end of civilisation. However, emboldened by a nuclear umbrella, the regime could adopt a more aggressive posture towards Israel and its allies. Nuclear deterrence could grant the Islamic Republic a freer hand to use conventional force and provide the regime with the cover it needs to reconstruct its battered proxies.

While the nuclear breakout clock ticks, time may also be expiring on the Ayatollah regime’s grip on the region. Before the 7 October Hamas attack, Iran held a noose around Israel’s throat through its proxies in Hamas and Hezbollah. But since then, it has suffered a series of crushing setbacks.

Hamas, Iran’s closest Palestinian ally, is out of the picture, its war machine dismantled. Iran can no longer send weapons or provide training to Hamas in Gaza. On 13 April 2024, Iran fired 300 missiles and drones at Israel; 99 percent of them were intercepted by Israel with the help of an international coalition. Iran’s difficulty in penetrating Israel’s air defences exposed the technological gap between the two countries. Equally important was the fact that an international alliance was willing to mobilise in defence of the Jewish state. On 19 April, Israel retaliated—a response that turned out to be merely symbolic. Then, on 1 October, Iran struck Israel directly for a second time—which was also largely unsuccessful. One day after this attack, as the Iranian defence establishment braced for the Israeli response, Iran expert Arash Azizi reported that officials connected to the military were expressing dread at the prospect, since, as one of them said, “We don’t have a fucking air force.”

That concern proved valid: On 26 October, Israel wiped out Iran’s remaining S-300 air defence systems and destroyed multiple radar sites as well as several key weapon production facilities, leaving Iran’s skies vulnerable and halting its ballistic missile and solid fuel production capabilities. No Iranian air force was anywhere to be seen.