Isabel Kershner THE case of the Israeli soldier who shot an alleged Palestinian assailant in the head as he lay wounded and subdued on the ground is whipping up a public and political storm and posing a rare challenge to the military's high command, usually the most popular body in the country. In a letter sent to commanders and soldiers on Wednesday, Lt. Gen. Gadi Eisenkot, the chief of staff, underlined the predicament facing the army as it contends with a surge in Palestinian violence — and faces a hardened public mood fanned by some politicians who say Palestinian assailants must not be left alive. "The commanders, and I first among them, will continue to give backing to any soldier who errs in the heat of battle against an enemy endangering the lives of civilians and soldiers," Gen. Eisenkot wrote. "That said, we will not hesitate to fully implement the law against soldiers and commanders if they deviate from the operational and moral standards according to which we work." Posters appeared in Tel Aviv soon after the shooting depicting Gen. Eisenkot, who had swiftly condemned it. Urging the general to resign, along with the prime minister and the defense minister, the posters bore the legend: "Jewish blood is not to be abandoned. He who rises up to slay you, slay him first." After six months of Palestinian stabbing, shooting and vehicular attacks against Israelis, a simmering debate has burst into a heated argument over what constitutes appropriate use of force and what is excessive. While many Israelis have denounced the shooting last week, which was caught on video, as a grave breach of proper military conduct, many others call the accused soldier a hero. By Wednesday nearly 57,000 Israelis had signed an online petition demanding he be given a merit citation. Education Minister Naftali Bennett has accused the leadership of being "quick to pounce on the soldier." He and other right-wing politicians, activists and the soldier's family are now waging a campaign against Defense Minister Moshe Yaalon and the army's top officers. Israelis have voiced outrage on social media over what many see as too hasty a judgment by the political and military leadership and by an initial pronouncement by the military prosecutor that the soldier was under investigation on suspicion of murder. Supporters claim he has been abandoned by the system that should be backing him. Experts said the emotional response partly reflected a natural empathy for soldiers. "This is a test," said Udi Dekel, an expert in civil-military relations at the Institute for National Security Studies at Tel Aviv University. "On the one hand," he said, "the army has to be attentive to the feelings of the people." On the other, he said, "you cannot run an army based on social networks and relatives." And the military cannot change the rules of engagement because of a political and public onslaught, said Dekel, a former brigadier general. The episode began last Thursday, when two Palestinians stabbed and wounded an Israeli soldier at a checkpoint in the West Bank city of Hebron. His fellow soldiers shot them both, killing one and wounding the other, who was identified as Abed Al-Fatah Al-Sharif, 21. The accused soldier arrived at the scene about six minutes later, by which time calm appeared to have been restored. The video shows him cocking his rifle and shooting Sharif, this time in the head, as he lay on the road. Lawyers representing the soldier say he acted to save his comrades in the belief that Sharif, who was still moving, might have been concealing an explosive belt under his jacket. The soldier did not warn others to move away from Sharif, and had Sharif been wearing explosives, critics noted, the soldier's shot could have detonated them.