The US president has given the Iranians a choice: negotiate or face devastating escalation.
The next move is down to Iran’s supreme leader, Ayatollah Ali Khamenei.
He has spent his entire life trying to roll back American power and influence in the region.
Expecting him to negotiate with the US now, with B-2 bombers held to his head, is a tall order.
More likely, he will order some kind of retaliation – at least for now.
He will want to deter Donald Trump from launching more attacks and may calculate that killing Americans is the best way of doing so.
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The ayatollah knows that doing so could drive a wedge between Trump and his MAGA supporters, who say America is getting drawn into yet another Middle Eastern war, risking US lives.
There are plenty of US targets for Iran to aim at, with bases throughout the Middle East: in Qatar, Kuwait, Iraq, and Saudi Arabia.
The Iranians could attack them directly with drones and missiles, or use proxies in the region, Iran-backed militias in Iraq, or the Houthis, based in Yemen.
Iran could threaten shipping and the oil industry in the Persian Gulf. If the Gulf becomes a war zone, expect a big hit to the global economy and the price of oil to rocket.
But all that would invite massive retaliation from the US. The Trump administration has spelt that out in no uncertain terms.
America has sent an awesome amount of firepower to the region: three aircraft carrier groups bristling with fighter jets and submarines loaded with cruise missiles.
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So the Iranians may instead go for the kind of asymmetric warfare they excel at. The UK could be in the firing line too. We could see Iranian terrorist attacks here in Britain.
One way or another, this is almost certain to escalate, but could it widen and draw other countries into the conflict?
Russia and Iran have a strategic partnership agreement, but it doesn’t require Russia to come to Tehran’s support.
Iran is also China’s closest ally in the Middle East, but Beijing is also likely to sit this one out and watch from the sidelines.
Wars have unintended consequences, but there are strong reasons for other powers to avoid becoming involved in this one.
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Looking further ahead, there are two competing priorities to watch. For Iran’s leadership, it is all about survival, to absorb the blows and live to fight another day, and eventually build the bomb if it can, to stop this ever happening to them again.
And Israel is equally determined that will not happen.
One method would be regime change in Iran, but its leadership is proving resilient so far, despite the mounting challenges it faces.
Instead, Israel faces a long period of managing the threat posed by Iran.
It will need to monitor the Iranians, watching for signs they are developing their missile programme, meddling in the region or reviving their nuclear project, and cut them down to size when necessary.
That could mean years more of military action and could be hugely costly for Israel and its backers, the US taxpayers.
In summary, Iran’s leadership is in a very tight spot and is likely to lash out, but the future will not be a walk in the park for Israel, either, while there are big risks for America, too.
