A formal declaration of war has not been made but it looks and sounds like war in central Tehran.
Clouds of smoke and the crack of high explosives rupture the air as the Americans and the Israelis bring their operation to the heart of the capital city.
And if the elimination of the senior Iranian leaders was their chief objective, it seems they have achieved their goal.
Live updates on strikes
The death of the Supreme Leader, Ayatollah Ali Khamenei, was acknowledged on state television at 4am on Sunday. The presenter recited a prayer for the dead - but he was barely able to finish it as he choked back the tears.
In stark contrast, the demise of the supreme leader has been met with a burst of exuberance and sheer joy in locations throughout the country.
"Congratulations on our freedom", cried one in the back seat of a car.
"Am I dreaming? Hello to the new world!" shouted another in southern Iran, as he watched people tear down a monument to Ayatollah Khomeini, the founder of the Islamic Republic.
In Tehran, many cheered from the windows and lit fireworks from their balconies. Khamenei ruled Iran with an iron fist - an autocratic leader prepared to repress and kill his own people to protect the regime.
But in a deeply polarised society, he was also a revered religious figure - a man invested with the authority of the divine.
Anger and shock among some Iranians
In Tehran's Revolution Square, his supporters spoke of their anger and deep shock.
"We were saying to ourselves all night that his death must be a lie. Unfortunately, it was the truth," said one woman, as her body shook heavily with emotion.
"We lost our dearest person, we lost our elder, we lost our master," said another tear-stained man.
Read more:
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President Trump says he has given Iranians the opportunity to take back their country but it is clear that a significant number back the existing regime.
A regime this coalition of two is now trying to destroy.
We saw the remains of the police headquarters in Tehran and the bombed-out shell of the Revolutionary Prosecutor's Office, where many political dissidents have been sentenced to death.
One massive blast claimed the detention facilities used by the feared paramilitary police or 'Basij'.
The regime certainly looks vulnerable as the Americans and the Israelis operate with what appears to be total air superiority.
Yet the clerics and their supporters remain and they control the streets.
(c) Sky News 2026: Iran's regime looks vulnerable - but clerics and their supporters still control the streets
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