The aim was to spread the word that the device, nicknamed the Silent Guardian, is neither sinister nor dangerous. In an age when the US military has been dogged by allegations of torture at secret bases, such perceptions are crucial.

I would think they are... though the thought of people being frazzled to ashes never even crossed my mind!

The development of the weapon only became public after the Sunshine Project - a Texas-based group that campaigns against biological and chemical weapons - pushed for disclosure under the Freedom of Information Act.