Met Office Assistant Commissioner says fanatics ' tactics have changed . Comment: ISIS uses videos like those featuring Jihadi John to inspire followers . Extremists are now targeting the mentally ill and very young , he said .
Met Office Assistant Commissioner says fanatics ' tactics have changed . Rather than large-scale 9/11-style attacks , smaller cells are now forming . ISIS uses videos like those featuring Jihadi John to inspire followers . Extremists are now targeting the mentally ill and very young , he said .