In the span of a few days earlier this month, developments that usually sit in separate policy compartments began to converge. Abu Dhabi’s crown prince arrived in Beijing as President Xi Jinping used the visit to set out China’s four-point position on the Iran war. Pakistan, now central to keeping US-Iran diplomacy alive, said no date was fixed for the next round of talks. Washington escalated pressure on buyers of Iranian oil and the banks handling related funds. Reports circulated of yuan use...