Letting the enemy keep guessing about how much you know, and how much you recovered, forces them to waste time and resources trying to figure it out. It's likel

Letting the enemy keep guessing about how much you know, and how much you recovered, forces them to waste time and resources trying to figure it out. It's likely to promote additional missions which in turn will give you an indication of how valuable they consider whatever it was, and if you have intelligence on who's contacting who, it also tells you who the operation might have been under and thus the overall disposition of their government. There's endless good reasons in the intelligence business to keep things secret.