[snip]
Northrop Grumman's Guardian system features a 50-pound pod, shaped like a small, upside canoe, fitted to the belly...The system operates independently of the aircraft's pilot in identifying a missile threat and then firing a burst from a laser that forces the attacking missile to "make a violent turn" away from the aircraft, said Jack Pledger, director of Infrared Counter Measures Business Development for Northrop Grumman. The process takes about two to three seconds, faster than a human could react under the circumstances, he added.
Aviation Daily, 9/13/06
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BAE Systems tested another system on a Boeing 767.
http://www.homelandsecuritynys.org/news/2005/tr21116.pdf