I thinkt the whole idea of Detachment 2702 is hilarious. It's all a game of "I know that you know that I know that you know..." They have the information and they want to act on it, but they have to pretend like they don't have it. But it gets complicated with the sinking of the merchant ships because the merchant shipping code was broken. The Germans crack the Allies merchant codes. The Allies have cracked the German code so they know this. So then the Allies have to change the shipping code But if they change the shipping code, the Axis will know because they will intercept it and realize it's different. So they will change their code. And then the codes keep changing.
You crack the code. Then they realize and change theirs. Then you crack it again.
Vicious cycle it sounds like.