In the criminal complaint against Mr Khan, a student at the University of Texas, an undercover FBI source said an unnamed co-conspirator was introduced to him as a contact for “brothers” travelling from Britain to Somalia, apparently to fight with al-Shabaab. The co-conspirator told the FBI source, who posed as a US-based Somali who wanted to fight with the al-Qaeda-affiliated group, that “brothers from the UK … would guide” the source when he travelled to Somalia. Using codewords, the co-conspirator said that the FBI source would have to undergo training but that he would not have to travel to Britain for this, as the “brothers are already in the field in ‘Mog’ ” – taken to be a reference to the Somali capital, Mogadishu.