“Third, war crimes which are grave breaches of the Geneva conventions in the context of armed conflict and include, for instance, the use of child soldiers; the killing or torture of persons such as civilians or prisoners of war; intentionally directing attacks against hospitals, historic monuments, or buildings dedicated to religion, education, art, science or charitable purposes.”
Bombing civilians and lying about it is probably a good place to start.
The International Criminal Court has no jurisdiction here.
Anyone with sufficient firepower can convene such a tribunal, and enforce the outcome.
Without that firepower, you’re a joke.