Just lately in the UK we've had Red Mercury, Forest Gate, Ricin and the Liquid Explosive plane bombers. But red mercury is a con, home-made binary explosives are hard to believe (as a weaponised, deliverable threat -- and so is ricin), and Forest Gate saw 250 Babylon fail to find the cyanide bomb they knew was there...
It looks worrying:
- British security forces are so gullible they think that mugs pursuing non-existent weapons are dangerous
- British security forces are so gullible they think it's practical to manufacture explosive from harmless-looking liquids
- British security forces are so gullible, they think that cyanide and ricin are practical weapons
- These threats actually exist, and are definitely more likely than jiggering an Li-ion laptop battery to burn through the cabin wall, swallowing remote-detonated explosive packages like a cocaine smuggler, or any of the obvious infrastructure attacks
[Updated years later, 24/10/2010 with helpful links: http://xkcd.com/651/ and http://www.theregister.co.uk/2009/09/21/bum_bombing/]
A lot of lightly-educated male muslims in the UK are flaming away to each other about the war against Islam, the punishment that the West deserves, and the luscious fantasy glamour targets that can be conjured up by someone who doesn't actually have to plan and execute a terrorist attack.
These men are on a continuum. Some just blether. Some go a stage further and do something really dorky like buying a tonne of fertiliser -- ending up incriminated as can be, but no nearer the ANFO bomb they seek. And some have the capability, intention and a target.... and since speech is free, it's only these last who really matter. And, in the nature of things, they're rare -- colossally outnumbered by the tens and hundreds of thousands who agree, but won't go beyond ugly talk. So why arrest and prosecute people who were unlikely to achieve subtantial acts? The answer is the source of the "intelligence" which is identifying these nutters: communication intercepts. If GCHQ isn't automatically scanning at least some emails, IMs and blogs for dodgy words and links, I'll eat my hat. And if these automatic scanners can distinguish between real threats and radical show-offs, I'll eat my knickers.
Here's the problem -- a real, valuable source of hard intelligence is being undermined by noise. Too many hits to use. What's needed is a way to ensure that the only people sending incriminating commumunications are those prepared to risk arrest. And here's the solution: arrest, and prosecute, to send a message:
MI5 to loudmouth radical muslims: "Shut the fuck up so we can listen to the good stuff. Or we will wreck your life."