The second strike certainly looks like a war crime (or, given that the US is not at war with Venezuela, just plain old murder), but sadly there is no chance of anyone being held to account under international law, as the US doesn't sign up to it.
We can only hope that enough GOP Senators and Representatives grow a spine so that Hegseth, Admiral Bradley, and everyone below Bradley in the chain of command can be held to account through the US Justice system.