Ken Roth at Human Rights Watch:
The alternative to war constrained by the laws of armed conflict, or international humanitarian law, is what is known as total war—war fought without any effort to minimize harm to civilians; indeed, war fought to maximize civilian harm as a deliberate strategy. War is ugly, but total war is worse. That’s the way, for example, that Russian and Syrian forces fought in Syria, and how Russian forces are now fighting in Ukraine. The civilian toll can be enormous.
So while there is no doubt that aggression should be opposed, should an organization like Human Rights Watch, as it seeks to uphold the Geneva Conventions and other laws of war, also address the crime of aggression? Given the practical difficulty of doing both, Human Rights Watch prioritizes upholding international humanitarian law, because of its demonstrated importance in saving lives amid armed conflict. We leave it to others to oppose aggression.
Fortunately, while violations of the laws of war are frequent, overt abandonment of international humanitarian law is less common.
More here.