Reading the Electronic Intifada's report on how U.S. corporate media coverage of Gaza "blindly asserted Israel's right of self-defense regardless of what was happening on the ground" reminded me of a passage in the book I'm reading, Jared Diamond's The Third Chimpanzee. Diamond argues that the ability to exterminate other groups of our own kind is something that we share with our closest animal relatives, pointing out that genocide in human history is not as uncommon as you'd like to think.
He identifies three mechanisms by which genocide is justified by groups that claim to subscribe to a universal code of justice. Two of them I think are fairly well-known: "Possessing the 'right' religion or race or political belief, or claiming to represent progress or a higher level of civilization, is a…traditional justification for doing anything, including genocide, to those possessing the wrong principle"; and "modern genocidists routinely compare their victims to animals in order to justify the killings."
Diamond's other rationalization, though, is not as obviously associated with genocidal violence:
Most believers in a universal code still consider self-defense justified. This is a usefully elastic rationalization, because "they" can invariably be provoked into some behavior adequate to justify self-defense. For example, the Tasmanians delivered an excuse to genocidal white colonists by killing an estimated total of 183 colonists over 34 years, after being provoked by a far greater number of mutilations, kidnappings, rapes and murders. Even Hitler claimed self-defense in starting World War II: He went to the trouble of faking a Polish attack on a German border post.
So while it might seem odd to cite "self-defense" as a rationale for unleashing violence that kills hundreds of times more people than the violence it supposedly is a response to, such claims are actually a standard justification for attacks on the relatively powerless. Ideally, though, journalists would be highly skeptical of accepting an argument that has been one of the main tools for rationalizing genocide.