Oman’s Sultan Haitham bin Tarik, whose Gulf country has been a long-time mediator between Iran and the West, arrived in Tehran on Sunday for a two-day visit. His trip comes just two days after Tehran freed Belgian aid worker Olivier Vandecasteele from almost 15 months in custody in exchange for diplomat Assadollah Assadi, who was held in Belgium over a 2018 plot to bomb an Iranian opposition rally outside Paris.
