What would it take for Donald Trump to call off air strikes against an Iran that's told Omani mediators it sees a pathway to compromise over its nuclear programme? We delve into where the veteran Tehran team of veteran negotiators can entice US envoy Steve Witkoff, whose red lines sometimes include the Islamic Republic's missile programme, sometimes less so. 

Neither side is drawing much attention to the actual situation inside Iran, where after the thousands killed in New Year's protests, fresh dissent has erupted as Amnesty International warns of looming executions of tortured demonstrators, some as young as 17.

Watch moreExclusive: Iran, massacre under a blackout

Watching from the sidelines are France, Germany, the UK and the other signatories of the 2015 UN agreement that Trump ripped up in 2018.

Where to put the accent? And what's this showdown ultimately about?

Produced by François Picard, Antonia Cimini, Juliette Laffont, Ilayda Habip, Charles Wente.