Here, it is official: Western human rights and aid groups justify and rationalize Saudi murder of civilians in Yemen

"One reason for high civilian casualties and damage to infrastructure, aid and rights groups say, is the fact that the fighting is concentrated in dense urban areas where it is more difficult to distinguish between targets."  If those justifications were provided about Syrian and Russian bombing in Syria, those who peddle the justifications would be accused of sympathy with war crimes and dictatorship, and accused of war crimes.