In most situations we should resist simplification but occasionally a moral question is simple.
Should a maniac take over the house opposite me and begin shooting at my house, even killing a member of my family, desperate though my situation would be, state forces could not destroy the house opposite until the family living there had left. Failing that, they would have to find a way of shooting or capturing the gunman. Until then I would have to endure.
Hamas murderers, using civilians as a shield, fired rockets into Israel. Israel cannot respond with shells, bombs and missiles.