During WW2 many Australian operatives inserted behind Japanese lines by submarine, parachute or boat fell into the hands of the enemy who were waiting for them as they landed. Tokyo Rose taunted troops by precise descriptions of their units, numbers, and where they were going. It became obvious a mole was in Australian high command.
To counter this, secret squadrons were formed. Crews were ordered to tell no one including their families about their work. Airfield air controllers did not know when they were to arrive or depart. This was extremely stressful on their loved ones when they received the dreadful telegram notifying of death, not knowing where they died or how.
The crews were segregated from other crew members before a mission. When inserting operatives they were given cyanide capsules as an option. The crews did not know what the operatives carried or details of their work; on the basis what you don?t know you can?t tell.