> technically speaking a peace treaty was never signed and North Korea is in the state of war with the United States. So is it really a crime to attack a hostile state?

that seems to be standard US foreign policy. it's probably actually worse in reality; where the US even 'intervenes' even if it does have a peace treaty with them. [1]

[1] https://en.wikipedia.org/wiki/United_States_involvement_in_r...