I just lost playing the "Battle Ocean '64 - Baltic Convoy". Main goal in this scenario is to escort the huge convoy from West Germany to Poland, and possibly avoid any enemy (Soviet) units on the way. During the course of the play, the enemy was able to sink two of my units using torpedoes. After that, they were still visible as "unfrendly" to me, so they don't attack me openly: their fighters just intercept my forces without opening fire, and their Navy don't use guns. They somehow attacked me without turning hostile.
My question: Is it possible to attack the other side without changing the side classification to "hostile"? Is it up to scenario settings, or maybe just some units are able to silently engage the enemy without rising an alarm? I lost because I just answered with fire and attacked the unit that I thought fired a torpedo: it was a Soviet Corvette that was trailing my unit. And then all of their units turned red and the hell broke loose.
Also I noticed the messages poping up in the message window before, informing me about the torpedo fail. That means that they've tried more than once. By the way, this message window sometimes gives away some important info about the enemy