No wars end on a whim. Some conflicts are plotted for years. A few, such as President Donald Trump’s conflict with Iran, begin in a moment of hubris. But the termination of wars is a grimly calculating business. When deciding whether to fight on or stop, belligerents must weigh tough choices—and even their own prospects of survival.

To predict when a war might end, you must first know each side’s incentives. In the Iran war this is an asymmetric task. Mr Trump broadcasts his wishes in real time, condemning the world to live inside his head whether it wishes to or not. Iran’s interests are far harder to read, but will shape everything from world energy markets to Middle Eastern stability and the chances of a global nuclear arms race.

For that reason (and in an attempt to escape from Mr Trump’s blond-thatched cranium, if only for 45 minutes) tomorrow’s episode of Inside Geopolitics focuses squarely on Iran. I have asked two experts to join me in The Economist’s London studio: Sanam Vakil, the Iran-born director of the Middle East and North Africa Programme at Chatham House, and Sir Simon Gass, a former British ambassador to Tehran and a senior negotiator of the Iran nuclear deal in 2015.

There is so much to explore. Iran’s new supreme leader, Ayatollah Mojtaba Khamenei, has not been seen since Israel and America killed his father (and predecessor as supreme leader), along with his mother, wife and sister in air strikes on February 28th. Many more leaders were killed in the days after. Mr Trump has variously claimed that, thanks to those killings, Iran is now led by pragmatists begging for a deal, or by sick and crazy people, or—if you believe his words at a cabinet meeting at Camp David last week—by men whose will to fight will “peter out” under his attacks.

Iran’s neighbours fear that February’s decapitation strikes radicalised the regime, weakening the clerical establishment and empowering hardline nationalists from the Revolutionary Guard. If true, what does that mean for the war?

Are Iran’s leaders united? Do they want to use control of the Strait of Hormuz to extract the best terms from America, or as a chokepoint that gives them power and toll revenues forever? What of Iran’s long-suffering people, thousands of whom were slaughtered by the authorities this year, before bombs and missiles began falling? Dr Vakil offers a sober summary: “This is a state that has been [having] a legitimacy crisis for decades now, but it has proven in the course of six months that it can repress its population and stand up to the US and Israel. And that sends, I think, a very bleak message for ordinary Iranians.” Sir Simon is not much more cheerful. He believes that Iranian decision-makers see the conflict as a mere “punctuation mark in a 40 year contestation with the United States”. How might it end, then? Tune in tomorrow to hear their answers. And, as ever, once you’ve watched the show please send in your thoughts and feedback. Write to me at insidegeopolitics@economist.com.