Insurgents in southern Thailand have begun using keyless-entry systems from cars to trigger bomb explosions after authorities took to blocking mobile-phone signals.
The Bangkok Post reports that Thai police found a Daihatsu RF key near a blast site in Yala on April 13. It is thought the bomber dropped it while fleeing the scene. The key had apparently been modified so its signal covered a longer distance.
Police believe that insurgents may have obtained up to 40 of the devices, and have distributed photographs to southern stations.
According to the Post, "militants who have in the past used mobile phones to set off bombs are being forced to change their detonation methods as security forces continue to block mobile phone signals while carrying out security missions," suggesting that Thai security forces routinely jam or otherwise block mobile-phone frequencies as they go about their business.
The Thai government seems to be claiming this shift in insurgent tactics as a success for the authorities, though it might well be seen the other way round.
Similar electronic-warfare battles are now being fought between Coalition forces and their enemies in Iraq, and in former times by Northern-Irish republicans and British forces.
Heavy-handed active jamming, apparently favoured by the Thais, has seldom been used on the UK mainland. It causes massive disruption to civilian communications, and in any case the emergency services frequently need to make use of mobile comms themselves. There is also some risk of triggering a device by one's own jamming signal, though this mainly affects older and more basic devices.
And the Thai forces are finding out the same thing that the British army did long ago: that as soon as you block one signal the enemy will think of something else. The Provisional IRA in their day would often wire up a bomb to a speed-trap detector, for instance, and then trigger it from a distance using a radar gun. Other ploys used by various organisations have included hospital beeper systems, remote controls from toys, light sensors set off using camera flashes etc. As consumer wireless technology continues to proliferate, the options for the bomber will widen. WIMAX, anyone?
This is a struggle which won't end any time soon. ®
Lewis Page is a former bomb-disposal officer.