Five years ago, a British-born Muslim flew to New York’s John F. Kennedy airport for what US officials maintain was an eight-month reconnaissance mission for al-Qaeda.

American investigators allege that he and two other Britons collected details of some of the most iconic buildings in global finance: the International Monetary Fund’s head office in Washington, Prudential’s world headquarters in Newark, New Jersey, and the New York Stock Exchange and Citigroup Center in Manhattan. His goal, according to an indictment in New York in April, was to help put together an attack plan that included use of a weapon of mass destruction.