Excellent point. Time to find out what counts as "time of war" these days, as formal declarations seem to have gone out of style, at least in the US, in the mid-twentieth century.

(To the best of my knowledge, not only is Korea a frozen conflict, but also the Chinese Civil War.)

Edit: my casual surfing has only turned up rules for how to behave once armed hostilities have started. Outside of that case (and assuming the US even considers itself covered by IHL these days), things seem to devolve to "δυνατὰ δὲ οἱ προύχοντες πράσσουσι καὶ οἱ ἀσθενεῖς ξυγχωροῦσιν".