A senior Israel Air Force officer articulated the challenge from above. Pilots take to the sky with the instruction "to avoid to the greatest extent possible harming civilians," said Brig. Gen. Yaron Rosen, the IAF Air Support and Helicopter Air Division Commander.

And yet, during the course of the current operation, he said, he saw, for example, "a fan" of 15 rockets scream skyward from Beit Hanoun, in northern Gaza. Immediately, he could see, from his command position, where they were headed: Ashdod, Kiryat Gat, Tel Aviv. As he zoomed in on the point of fire he saw that the rockets were launched from an underground launcher "on the fence" of a boys and girls school.

Returning fire, destroying the rocket launchers, he said, would probably damage the school. Perhaps there were children inside. "What do I do? What do I do now?" he asked.

The air force, he said, had held its fire and spared the lives "of hundreds of Hamas operatives" and assets in order to avoid hurting innocent people.

"When are civilians killed?" he asked. "When there's no time. When there is fire directed at the citizens of Israel."

"A state," he added, "has to tend to its own citizens."

Rosen seemed genuinely awestruck by the extent of the military infrastructure embedded in civilian and humanitarian complexes in Gaza. He used the words "unfathomable" and "insane" on several occasions. He described Al Wafa Hospital, which Israel bombed after it had been finally emptied, as the central command post from which Hamas directed the bloody battle in Shejaiya. "It was a hospital held hostage by Hamas," he said.

How Gaza perverts the army's rules of engagement