International Law is great when there's some incident between nation states, but there's a dire need for intra-national law, where nations can poke their noses into the affairs of an aggressor government.

Case in point: Russian actions in Chechnya back in the early 2000s. When there were murmurs of disapproval, Russia basically just told everyone: "Go away, it's an internal problem." And, shamefully, everyone did just that.