Bad move. Mondelez is probably going to have to prove that the US is actually at war with whomever delivered NotPetya (NP). NP might well have been developed for the Russian state or not (who cares - its still nasty) but that does not constitute war.
The US and Russia are not at war: there is no merit in trying to claim otherwise. It might be considered inflammatory and perhaps reckless to imply a state of war might exist.