US boasts of laser weapon's 'plausible deniability'

     * 15:45 12 August 2008
     * news service
     * David Hambling

An airborne laser weapon dubbed the "long-range blowtorch" has the 
added benefit that the US could convincingly deny any involvement 
with the destruction it causes, say senior officials of the US Air 
Force (USAF).

The Advanced Tactical Laser (ATL) is to be mounted on a Hercules 
military transport plane. Boeing announced the first test firing of 
the laser, from a plane on the ground, earlier this summer.

Cynthia Kaiser, chief engineer of the US Air Force Research 
Laboratory's Directed Energy Directorate, used the phrase "plausible 
deniability" to describe the weapon's benefits in a briefing 
(powerpoint format) on laser weapons to the New Mexico Optics 
Industry Association in June.

Plausibly deniable

John Corley, director of USAF's Capabilities Integration Directorate, 
used the same phrase to describe the weapon's benefits at an Air 
Armament Symposium in Florida in October 2007 (see page 15, pdf 

As the term suggests, "plausible deniability" is used to describe 
situations where those responsible for an event could plausibly claim 
to have had no involvement in it.

Corley and Kaiser did not respond to requests from New Scientist to 
expand on their comments. But John Pike, analyst with defence 
think-tank Global Security, based in Virginia, says the implications 
are clear.

"The target would never know what hit them," says Pike. "Further, 
there would be no munition fragments that could be used to identify 
the source of the strike."

Silent strike

A laser beam is silent and invisible. An ATL can deliver the heat of 
a blowtorch with a range of 20 kilometres, depending on conditions. 
That range is great enough that the aircraft carrying it might not be 
seen, especially at night.

With no previous examples for comparison, it may be difficult to 
discern whether damage to a vehicle or person was the result of a 
laser strike.

The 5.5-tonne ATL combines chlorine and hydrogen peroxide molecules 
to release energy, which is used in turn to stimulate iodine into 
releasing intense infra-red light.

The US uses Hercules aircraft for accurate cannon strikes on moving 
vehicles. The ATL is touted as bringing a new level of accuracy to 
such attacks, for example being able to pinpoint a vehicle's tyres to 
disable it safely.

A second, larger version of the laser is also nearing initial 
testing. The much larger Airborne Laser is intended for missile 
defence and will be carried by a Boeing 747.

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     * ATL official fact sheet, USAF (PDF format)
     * John Corley's presentation - see page 15 (PDF format)
     * Cynthia Kaiser's briefing (PowerPoint format)