The US has carried out a "very successful attack" on three nuclear sites on Iran, President Donald Trump has said, while Tehran has warned of "everlasting" consequences.
Bunker buster bombs were dropped on the heavily protected Fordow enrichment plant, which is buried deep under a mountain near the city of Qom, as well as sites at Natanz and Isfahan.
Satellite imagery has revealed some of the surface damage at Fordow after the US strikes.
The dramatic escalation brings the US into direct involvement in the war between Israel and Iran. Tehran's threat of reprisals raises fears of a wider regional conflict.
Follow latest: US bombers strike three Iranian nuclear sites
Iran's foreign minister Abbas Araghchi warned that the US strikes "will have everlasting consequences", adding that his country "reserves all options" to retaliate.
US defence secretary Pete Hegseth said America's 'Operation Midnight Hammer' had "devastated the Iranian nuclear programme" but confirmed the strikes were "not about regime change".
"The United States does not seek war, but let me be clear - we will act swiftly and decisively when our people, our partners, or our interests are threatened," he said.
Iran has repeatedly denied that it is seeking a nuclear weapon, and the head of the UN's nuclear watchdog said in June that it has no proof of a "systematic effort to move into a nuclear weapon".
The Iranian foreign minister told journalists on Sunday morning that he was flying to Moscow to have "serious consultations" with Vladimir Putin.
He described Moscow as a "friend of Iran", adding: "We always consult with each other."
Iran's Revolutionary Guard Corps (IRCG) said that "invaders must now await responses that will bring regret" after US strikes.
Iran has requested an emergency meeting of the UN Security Council to "maintain international peace and condemn the US strikes", according to state media.
Israeli Prime Minister Benjamin Netanyahu hailed the "bold decision" by Mr Trump, saying it would "change history".
Read more:
What we know about the US strikes on Iran's nuclear facilities
Iran's Revolutionary Guard said it launched 40 missiles at Israel on Sunday morning, including its biggest ballistic missile, the Khorramshahr-4.
Iranian missiles hit sites in northern and central Israel, including in Haifa, Ness Ziona, Rishon LeZion and Tel Aviv.
The UK is preparing to fly British nationals out of Israel, and Israeli airspace will temporarily open today for repatriation flights to land.
Countries trying to evacuate their citizens are waiting for the airspace to reopen fully to charter flights out.
Gulf states like Bahrain, Saudi Arabia and Kuwait, all home to US military bases, are on high alert after the strikes, with Bahrain urging drivers to avoid main roads and Kuwait setting up shelters.
The UK has also further increased "force protection" measures for its military bases and personnel in the Middle East to their highest level.
Nuclear negotiations 'blown up'
The UK's prime minister called on Iran to "return to the negotiating table" and reach "a diplomatic solution to end this crisis".
"Iran's nuclear programme is a grave threat to international security. Iran can never be allowed to develop a nuclear weapon and the US has taken action to alleviate that threat," said Sir Keir Starmer.
However, Mr Araghchi said the US and Israel had "blown up" negotiations and asked: "How can Iran return to something it never left, let alone blew up?"
Read more:
Iran's secretive 'nuclear mountain' and its protection
Analysis: If Israel breaks Iran it will end up owning the chaos
US Senator Chris Murphy posted on X after the strikes, saying that he and other senators received a classified briefing last week indicating that Iran did not pose an immediate threat through its nuclear program.
"Iran was not close to building a deliverable nuclear weapon," Senator Murphy said. "The negotiations Israel scuttled with their strikes held the potential for success."
Addressing the nation in the hours after the strikes, Mr Trump said that Iran must now make peace or "we will go after" other targets in Iran.
"There will be either peace or there will be tragedy for Iran far greater than we have witnessed over the last eight days," he said.
In a post on Truth Social, Mr Trump said: "All planes are safely on their way home", and he congratulated "our great American Warriors".
He also threatened further strikes on Iran unless it doesn't "stop immediately", adding: "Now is the time for peace."
Sky News understands there was no UK involvement in the strikes.
'Fordow is gone'
Among the sites hit was Fordow, a secretive nuclear facility buried around 80 metres below a mountain and one of two key uranium enrichment plants in Iran.
"A full payload of BOMBS was dropped on the primary site, Fordow," Mr Trump said. "Fordow is gone."
? Listen to Sky News Daily on your podcast app ?
There had been a lot of discussion in recent days about possible American involvement in the Iran-Israel conflict, and much of it centred around the US possibly being best placed to destroy Fordow.
Meanwhile, Natanz and Isfahan were the other two sites hit in the US attack.
Natanz is the other major uranium enrichment plant in Iran and was believed to have possibly already suffered extensive damage in Israel's strikes earlier this week.
Isfahan features a large nuclear technology centre and enriched uranium is also stored there, diplomats say.
'No increase in radiation levels'
US media reported that six 'bunker buster' bombs were used to strike Fordow.
However, most of the highly enriched uranium at the Fordow nuclear facility was moved to an undisclosed location ahead of the attack, a senior Iranian source told the Reuters news agency.
Personnel numbers were also reduced at the site, according to the report.
The International Atomic Energy Agency said that there has been "no increase in off-site radiation levels" after the US airstrikes.
Mr Trump said no further strikes were planned and that he hoped diplomacy would now take over.
In a briefing with journalists, Iran's foreign minister said Mr Trump had deceived his own voters over his promises not to get involved in any more "forever wars".
"While President Trump was elected on a platform of putting an end to America's costly involvement in forever wars in our part of the world, he has betrayed not only Iran by abusing our commitment to diplomacy, but also deceived his own voters."
(c) Sky News 2025: US warplanes strike three nuclear sites as Iran warns of 'everlasting' consequences