Claude has been involved in the planning of a war crime, for sure. But 'Anthropic has had zero issue with it' is an unfounded assertion that you are making up.

Fielding a fully autonomous kill bot is absolutely a war crime under the IHL; specifically, there is no current universe under which a bot can reliably tell a combatant from a non-combatant, or a civilian target from a military target, or act in a proportional manner.