Scenario: Japan and USA are not at war, but Japan will attack on this turn.
If the USA has DD's in sz 25 and 31, could this block an attack by the Japanese in sz 26 just prior to hostilities? if the attack must pass thru sz 25 or 31? or are these sea zones still considered friendly because no dice have been rolled yet?
I believe as soon as you make a combat move against a neutral power, all of their units are immediately considered hostile, so the destroyer would stall you. A sub or tranny obviously would not.