The ICC doesn’t try people in absentia. They have to come before the court in person. That’s been a struggle for the ICC over time. The ICC tries individuals. It does not try states. For instance, in the current conflict, Russia would not be a defendant, but Vladimir Putin could be a defendant.
Practically speaking, in order for Putin and other senior leadership to face any kind of charge, there would have to be regime change in Russia. If there were to be charges, and if Putin remains head of state, it becomes very complicated, as we’ve seen with other heads of state who have been indicted and then not brought to bear before the ICC for years because they take steps to avoid physical presence before the court. The most prominent example of this is the former president of Sudan, Omar Al Bashir.
War-crimes charges related to the inappropriate targeting of civilians are certainly on the list for consideration.
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