A day after the US sent 13,600-kilogram bunker-buster bombs crashing into the mountain above Iran's Fordow nuclear site, Tehran vowed to defend itself at all costs, American leaders urged Tehran to stand down, and pockets of anti-war protesters began taking to the streets in US cities.
In a post to the Truth Social platform, US President Donald Trump addressed the issue of regime change in Iran.
"It's not politically correct to use the term, 'Regime Change,' but if the current Iranian Regime is unable to MAKE IRAN GREAT AGAIN, why wouldn't there be a Regime change??? MIGA!!!" he wrote.
Iran and Israel continued to trade volleys of missile attacks, with an explosion in western Iran claiming the lives of half a dozen military personnel, according to an Iranian media outlet.
Earlier, Iran fired missiles that wounded scores of people and flattened buildings in Tel Aviv.
Tehran has so far not followed through on its threats of retaliation against the United States - either by targeting US bases or trying to choke off global oil supplies - but that may not hold.
Speaking in Istanbul, Iranian Foreign Minister Abbas Araqchi said his country would consider all possible responses. There would be no return to diplomacy until it had retaliated, he said.
"The US showed they have no respect for international law. They only understand the language of threat and force," he said.
Ali Shamkhani, an adviser to Iran's Supreme Leader Ayatollah Ali Khamenei, said on X, formerly Twitter, that the initiative was "now with the side that plays smart, avoids blind strikes. Surprises will continue!"
Trump, in a televised address, called the strikes "a spectacular military success" and boasted that Iran's key nuclear enrichment facilities had been "completely and totally obliterated".
But his own officials gave more nuanced assessments and - with the exception of satellite photographs appearing to show craters on the mountain above Iran's subterranean plant at Fordow - there has been no public accounting of the damage.
The UN nuclear watchdog, the International Atomic Energy Agency, said no increases in off-site radiation levels had been reported after the US strikes.
The agency's director General Rafael Grossi told CNN it was not yet possible to assess the damage done underground.
A senior Iranian source told Reuters that most of the highly enriched uranium at Fordow had been moved elsewhere before the attack.
Trump said the Iranian government "must now make peace" or "future attacks would be far greater and a lot easier".
In a step towards what is widely seen as Iran's most effective threat to hurt the West, its parliament approved a move to close the Strait of Hormuz.
US Secretary of State Marco Rubio, in a television interview, warned Iran against retaliation for the US strikes.
Rubio separately told another talk show that the US has "other targets we can hit, but we achieved our objective".
"There are no planned military operations right now against Iran," he later added, "unless they mess around."
The UN Security Council met on Sunday to discuss strikes on Iran's nuclear sites as Russia, China and Pakistan proposed the 15-member body adopt a resolution calling for an immediate and unconditional ceasefire in the Middle East.
UN Secretary-General Antonio Guterres said earlier the US bombings in Iran marked a perilous turn in the region and urged a halt to fighting and return to negotiations over Iran's nuclear program.
Israeli Prime Minister Benjamin Netanyahu told Israeli reporters the nation was very close to meeting its goals of removing the threats of ballistic missiles and the nuclear program in Iran.
Anti-war activists organised demonstrations on Sunday local time in New York, Washington and other US cities, with protesters carrying signs that read "hands off Iran".
