Iran's rulers are confronting their most serious challenge since their own 1979 revolution.
They're now countering on an unprecedented scale - a ferocious security crackdown and near total internet shutdown has been unleashed on a scale unseen in previous crises.
Some of the streets once engulfed by a roar of anger against the regime are now starting to go silent.
On Friday it was extremely crowded - the crowd was unbelievable - and there was a lot of shooting. Then Saturday night it became much, much quieter, a resident of Tehran told BBC Persian.
You would have to have a death wish to go out now, one Iranian journalist reflected.
This time, an internal upheaval is also compounded by an external threat, with President Trump's repeated warnings of military action coming seven months after the US carried out strikes on key nuclear facilities during a 12-day war between Iran and Israel, which left the regime weakened.
But, to use an analogy often used by the American leader, that has also given Iran another card to play.
Trump now says Tehran has called to go back to the negotiating table.
But Iran doesn't have a good hand: President Trump says he may still have to take some kind of action before any meeting; talks won't take all the searing heat out of this unrest.
And Iran won't capitulate to what have been the US's maximalist demands, including zero nuclear enrichment, which would cross red lines which lie at the very heart of this theocracy's strategic doctrine.
Whatever the pressure of this moment, there's no sign Iran's leaders are changing course.
Vali Nasr from the Johns Hopkins School of Advanced International Studies, author of the book Iran's Grand Strategy, states, Their inclination is to clamp down, to try to survive this moment, and then to figure out where they go from here.
This week may decide the momentum in this moment - whether Iran, and the wider region, is plunged into another bout of military attacks; whether brute force has completely put down these protests – as it has in the past.
Iran's Foreign Minister Abbas Araghchi told diplomats in Tehran today that the situation is now under total control.
Five days into a comprehensive communications blackout, a chilling picture still sneaks out into the world through Starlink satellite terminals, Iranian technical creativity, and courage.
Doctors' accounts of hospitals overwhelmed by casualties, grim videos of open-air mortuaries dotted by long lines of black body bags, voice notes sent to journalists expressing shock and fear are becoming more common.
The government doesn't deny the bloodshed; state TV is also airing images of makeshift mortuaries, even admitting some protesters have been killed.
The streets of Iran have been on fire. Government buildings have been set alight as anger burned. They are symbols of the system, but attacks on public property are condemned by the government as the work of terrorists and rioters.
Legal language has also hardened in this time - vandals will be charged with waging war against God and face the death penalty.
The authorities are trying to regain control in Iran following weeks of protests. The latest wave has been unique; it began when traders in Tehran went on strike following a currency collapse.
Despite the government’s quick, conciliatory initial response, protests quickly escalated, revealing a country beset by years of sanctions, mismanagement, and public unrest.
This moment may be pivotal for Iran, with underlying issues resurfacing and indicating that change could be inevitable, though unpredictable. History shows that when fervor meets force, the results can be dangerous.
