Very ancient law, yes.

Also: Our law only knowns in this regard only knows either peace and wartime, but no in-between state of state financed propaganda or partisan/guerilla warfare that could already be our current status quo.

Propaganda of course is very legitimate in peace times. Digital attacks might always be criminal action or plausibly deniable. Recruiting civilians happens by both e.g. Russian Federation for sabotage and Ukraine for printing missile, drone or mine parts, see drukarmy. But when one group of allies and another state behave the current way, "Spannungsfall" might be reached easily when policy makers declare that has now happened once again after the fall of the eastern block wall.