Barbarism means extremely cruel and monstrous behavior. In the context of (extreme) hardline Israelis, the explanation refers to their behavior sprouted from how they view and provenly treat the Palestinians as animals. Letting (decomposing) corpses of Palestinians they have killed in Gaza to the dogs and cats is a barbaric behavior. Even luring starving (little) boys to "aid points" then targeting on specific parts of their body, is to classify as barbaric. 

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