I think you have a fundamental misunderstanding here. War crimes are not judged by what a diligent investigation after the fact might find. It hinges on the information and judgement by those acting in the moment. You are a soldier told these armed people a click out are the insurgent group you are fighting? Of course you can engage them. And there is a similar lenient standard applied to whoever got that information in the first place. War by any other standard of course would be entirely unworkable.
That is not correct. If you are a uninformed soldier operating in a designated combat area here are the scenarios:
* Patently illegal conduct, according to common person principle, is always illegal. There are no legal exceptions.
* If you are fired upon you must return fire. Uniformed militaries are obligated to defend themselves. There are no exceptions to this, except the prior point. When these two points are in conflict the prior point always wins.
* Uniformed service members are required, by law, to follow orders given to them except for the prior two points.
That is the law. It does not matter what specific scenario finds tenable or practical, because combat is inherently challenging. In most cases this is highly impractical, which is why urban warfare is so challenging.
