The only real accomplishment he’ll get is non-US-controlled war crime trials for US military personell. Perhaps even politicians.

According to the Geneva conventions (which the US is a party to), the prospective war criminal’s state basically gets first dibs to prosecute their own war criminals. What this means is they can be game the system and be incredibly lenient - they just need to keep the appearance of impartiality.

A real alternative is another party stepping up. Historically that was the other side of the war, but today most likely an international org.