A presentation given by a US Air Force official may have - temporarily, at least - laid to rest one of the wilder and wackier secret superweapon conspiracy theories of recent times.

The superweapon in question is the dreaded "E-bomb", aka "Electromagnetic pulse weapon (EMP)" "High Power Microwave (HPM)" and so on, depending on the exact details.

Most people are familiar with the fact that a nuclear weapon gives off a powerful electromagnetic pulse when detonated. Just as an ordinary-strength RF transmission induces tiny electrical flows in receiving antennae, a nuclear bomb's much more intense EMP can cause damaging spikes in exposed electronic circuitry, potentially knackering it.

Ever since the effect was noted, various people have speculated that it would be interesting to use a suitable nuke, not to leave one's enemy atomised and/or glowing in the dark, but rather to fry all his electronics.

One way of doing so might be to let off the nuke just outside the atmosphere above the location to be EMPed. The eponymous Russkie space zappers in the Bond flick Goldeneye were supposed to be some kind of E-bomb, for instance.

Not many people have nukes at all, though. Even fewer have so many of these expensive things that they would expend them handing out a relatively mild electronic love-tap as opposed to actually killing and destroying their enemies.

However, a lot of people think you could generate usefully-powerful electro-zap effects using means short of nukes. Aviation Week reporter David Fulghum, a veteran electronic-warfare analyst, has long prophesied the advent of the microwave weapon. Just last January, he wrote that: "High-power microwave weapons may be on the verge of a high-speed turn toward the practical."

Highly-qualified* Australian aerospace zealot Dr Carlo Kopp has asserted that a poor man's HPM/EMP bomb driven by ordinary explosives would be a doddle to knock together.

The relative simplicity of the [e-bomb bits] suggests that any nation with even a 1940s technology base, once in possession of engineering drawings and specifications for such weapons, could manufacture them.

As an example, the fabrication of an effective [explosives-driven flux generator] can be accomplished with basic electrical materials, common plastic explosives such as C-4 or Semtex, and readily available machine tools... communications infrastructure in the West will remain a 'soft' electromagnetic target in the forseeable future... With the former CIS suffering significant economic difficulties, the possibility of CIS designed microwave and pulse power technology leaking out to Third World nations or terrorist organisations should not be discounted. The threat of electromagnetic bomb proliferation is very real.

Holy crap - the goddamn terrorists can slap one of these together, and knock out all of western civilisation Die Hard 4 stylee.