"History is written by the victors"
Is kind of a sentiment I apply to this. Throughout modern history both sides in virtually every conflict have been guilty of war crimes. The biggest difference is that people on the 'winning' side or (more powerful side in stalemates) have a tendency not to take action against their own side for unlawful actions. I can think of a couple of British examples; some which have never been pursued and others that we have been taken to court over (Kenya springs to mind www.guardian.co.uk/commentisfree/2012/apr/23/british-empire-crimes-ignore-atrocities).
Then you have people like Peace Envoy to the Middle East Tony Blair... much accused of war crimes himself.
Again and again its been proven that "one man's freedom fighter is another man's terrorist" and ideas about defence of the people and protecting lives are never whiter than white as there is almost always 'collateral damage' to the opposite side. I think as a general rule the biggest concern we should have is about 'disproportionate' use of force rather than necessarily who ends up being targeted.
War is never pretty. Civilians always die. And tbh, war crimes are often unfortunately, more to do with the eye of the beholder, their underlying beliefs/political affiliation and how fully aware they are of the actions of both sides in the conflict. And many, many are frankly ignored, covered up or excused in one way or another. There are exceptions to this where war crimes are very clear cut - acts of genocide for example. But for the most part, it tends to be about the ability of one party to report what happens and to be believed and taken seriously that is the bigger factor. If our media is biased in one way or another, stories of one side tend not to reach our ears.
They say the first casualty of war is the truth and its just so true. (The second is probably law).
My heart breaks over Palestine and Israel. I believe both sides can justify what they are doing to a greater or lesser extent atm even though I am a peacemaker at heart. Both have had civilians die. But ultimately more violence will never resolve the deeply entrenched beliefs and actually solve the problem.