All they have to do is select arbitrary groups of 10 to 20 fairly inept and useless recruits, put them in London or Paris, set them up with a plot which is scarey enough, let them go for a few months, then leak the plot and get the useless recruits caught.

No need to actually blow up a plane, they can cost us all this money and cause all this inconvenience with ever trying to smuggle a single bomb or box cutter onto an airplane ever again.

Once the technique is perfected, they'll be well position to manipulate our elections at will. Plant a few plots and leak their existence when appropriate.

This is what IT guys in security call "Social Engineering", on a grand scale.

I think there's a big, overblown German opera here: The Flying Lieberman, eternally condemned to putting a good face on losing close elections.