How far could it escalate? One year after Donald Trump decided to walk away from the Iran nuclear deal and days after he effectively banned the rest of the world from buying Iranian oil, Tehran is responding in kind - giving the other signatories of the 2015 UN-brokered agreement 60 days to get back on board or it'll suspend parts of its pledges. How far will it go in a week that's seen an alarming amount of sabre rattling?
