Two Pakistani oil tankers, the Shalimar and the Khairpur, have turned back from the Strait of Hormuz (the narrow waterway linking the Gulf to the Indian Ocean, through which roughly a fifth of the world's oil passes) after making three failed attempts to transit the passage, according to marine tracking data from MarineTraffic. The retreats coincide with a dispute over the movements of two US Navy destroyers, the USS Frank E. Petersen and the USS Michael Murphy, which Washington says entered the strait on 11 April to secure the waterway and survey possible sea mines — a claim Iran has flatly denied. US-Iran nuclear talks held in Islamabad concluded without an agreement after more than 20 hours of negotiations, leaving the strait under continued strain as both sides weigh further escalation or a fragile de-escalation.