It’s hair-raising stuff: Britain’s MI-5 is apparently monitoring some 1500 British citizens and converts to Islam who misunderstood the “inner, personal struggle” meaning of jihad and are or have already trained to conduct attacks inside the UK. And they received their training inside the UK.

The tactic of using recent converts to Islam as frontline jihadists isn’t new. Al Qaeda has wanted to build an army of so-called “lily whites” — people who have no criminal record and don’t fit the South Asian or Arab profile of Muslims — for years. The German plot against US bases that was foiled last fall involved German converts working with a Turkish national.

Over 1500 such misunderstanders of jihad could do an awful lot of damage.