The  tanker  Mercer Street off the port of the Gulf Emirate of Fujairah in the UAE. On July 29th two of its crew members   were killed off Oman in what appears to be a drone attack. Photograph:   Karim Sahib/AFP via Getty Images

Iranian-backed forces are believed to have seized an oil tanker in the Gulf off the coast of the United Arab Emirates, three maritime security source(...)