Yemen bomb-makers working on new devices

Bomb-makers in Yemen are determined to develop ever harder-to-detect devices to smuggle on board planes bound for Western countries, according to Whitehall officials. The number of British airports with security body scanners is now being doubled, from 10 to 21, in response. Three years ago, a bomb sent from al-Qaeda in Yemen was found on a plane at East Midlands airport, disguised inside a printer. Another reached Dubai airport. Since then, a further device was discovered in Yemen in May 2012. So just how serious is the threat? In the airline security business, they call them Artfully Concealed Devices: sophisticated bombs, mostly non-metallic with a hard-to-detect, "low-vapour explosive" like pentaerythritol tetranitrate (PETN), disguised inside ordinary, harmless items like shoes, underpants, soft drink bottles or even printer ink toner cartridges.