This is a dangerous moment. The ceasefire opened up a chance for diplomacy that looked for a short time as if it might make progress. Americans and Iranians faced each other across a conference table in Pakistan's capital, Islamabad, but came away empty-handed. The Pakistanis are trying to revive the process, without much success so far. Both America and Iran want to have a deal. But they have different deals in mind and are sticking to their red lines. Until one or the other, or preferably both, decide to offer concessions, renewed full-scale hostilities remain an incident away. More than ever there is a strong risk of misperception and miscalculation of intentions and consequences. Both are classic ways in which crises slip out of control and wars escalate.

America's decision to escort two ships through the Strait of Hormuz was always going to produce a reaction from Iran. This week's urgent question is whether it ends there or whether more action and reaction power a slide back into all-out war. Control of the Strait of Hormuz has become the central issue in the crisis. It was open to navigation, without restriction or the payment of tolls, until 28 February -when the US and Israel attacked Iran. Now Iran has demonstrated how closing it can mean everything from an offensive weapon to a revenue raiser and an insurance policy. This week, Iranian Foreign Minister Abbas Araghchi has told MPs that there will be no return to the old status quo. The US cannot allow Iran to make the Strait of Hormuz into home waters that the Tehran regime can control and use to charge shippers millions in tolls, without accepting that tactical victory over Iran's armed forces has become a strategic defeat. (BBC)