In the early hours of Saturday morning, President Donald Trump announced that the US had launched military strikes on Iran.
In an eight-minute video statement posted to social media, he said the US was undertaking a "massive and ongoing operation" to end the Iranian threat and he called for regime change in Tehran.
"It's a very simple message," the president said from his Mar-a-Lago resort in Florida. "They will never have a nuclear weapon."
The BBC's State Department correspondent Tom Bateman and Washington correspondent Daniel Bush break down the president's words line by line to explain how he is justifying the action and assess the risks ahead.
"Our objective is to defend the American people by eliminating imminent threats from the Iranian regime, a vicious group of very hard, terrible people. Its menacing activities directly endanger the United States, our troops, our bases overseas, and our allies throughout the world."
