International Red Cross issues rules for civilian hackers during war

"Please, don't commit acts of war all on your own, your State is supposed to join in with you"

Isn't it the policy of the USA that States can be held responsible for the independent acts of their citizens (or just residents), with consequences ranging up to full military engagement? Haven't multiple nations worked in concert with the USA to detain and punish "hackers" whose activities were found bad by the USA, regardless of the legalities?

Why shouldn't we expect any other government to take the same view?