Some comments have seemingly suggested that "Pillar of Cloud" might not evoke the same resonance in English that it does in Hebrew, and that "Pillar of Defense" makes the idea clearer. But does it? A pillar is not usually a defensive structure, while the imagery from the Biblical account is a fairly familiar part of the Western tradition. Or at least it is to me.
On the other hand, perhaps they were worried that some will misunderstand the Biblical allusion, as this article at Gawker seems to, as a symbol of "an all-powerful, vengeful God seeking to demonstrate the primacy of his chosen people," not, presumably the PR image the IDF was aiming for. But that is not really the implication of "Pillar of Cloud" in Exodus, for as this article on the Tablet Jewish site notes that the midrash on the Biblical text describes the pillar as defending Israel against the pursuing Egyptians (and not, as smiting them):
The midrash on this section—which is cited by Rashi, the most famous Jewish biblical commentator, and taught in many Hebrew schools—elaborates:In fact, as this article notes, the Talmud adds a layer of interpretation that may even contradict the image the IDF was presumably looking for:
They [the Egyptians] shot arrows and catapult stones at them, but the angel and cloud caught them.
According to the Talmud, the Pillar of Cloud was a special gift conferred upon the Israelites because of the merit of Aaron, Moses’s brother. And Aaron’s quintessential quality—the quality that would have earned him this gift—was that he was, well, a peacenik. The Talmud teaches in Pirkei Avot that Rabbi Hillel said, “Be among the disciples of Aaron—a lover of peace and a pursuer of peace; a lover of all people, bringing them closer to the Torah.” Another rabbinic text, Avot d’Rabbi Natan, makes clear that this attitude should be extended not just to Jews, but to all nations: “The phrase teaches us that a person should be a pursuer of peace among people, between each and every one.”
Whichever meaning was intended by the IDF in choosing the name, I still think that "Pillar of Defense" is an awkward choice in English: at worst, it may suggest they're trying to conceal the Biblical reference, as some have inferred.
I can’t speak for the entire Israeli public, but when I think “Pillar of Cloud,” this—Aaron’s legacy of peacemaking, and the rabbinic injunction to follow in his footsteps—is what springs to mind. So perhaps next time the IDF wants to exploit Israelis’ semantic field to sell them on a new military operation, they should do their homework first—or hire some good yeshiva students to do it for them.
Personally, I long for the days when military "codenames" really were code, not public relations tools (World War II operations like Torch and Overlord tell you nothing at all, which used to the intention of a codename.)