Iranian journalists in London have experienced death threats, intimidation and online abuse. One broadcaster working for BBC Persian, the Persian-language branch of the BBC World Service, which has its headquarters in London, had her car broken into, and her conversations with family members were tapped. And last month, Pouria Zeraati, a newscaster with Iran International, a Persian-language opposition TV channel that operates from Britain, was stabbed in the leg outside his London apartment. The three suspected perpetrators of that attack traveled to Heathrow Airport and left the country within hours, according to the Metropolitan Police Service, which is responsible for policing in London. Specialized counterterrorism officers are still investigating the motive behind the nonfatal stabbing of Mr. Zeraati, and the Met declined to say where the assailants had flown to. But experts say these targeted incidents are part of a frightening pattern of physical attacks, threats and surveillance that have become a reality for many Iranian journalists working abroad. And London, home to a number of Persian-language broadcasters, has become a “hot spot” for transnational …