Revealing specific information would identify an asset in the program. For example, if they confirmed that the warheads were made of thin sheet aluminum over w

Revealing specific information would identify an asset in the program. For example, if they confirmed that the warheads were made of thin sheet aluminum over wooden forms, there are a reasonably limited number of people who would legitimately have that information. A few more confirmations, and the number of people in the Venn diagrams of cleared individuals would be reduced. They need the informants to remain valuable. The informant should feel reasonably safe (or scared enough of the consequences of not complying) and able to maintain their access so that they can continue to provide or corroborate information. Leaking everything would get a lot of people killed. The intelligence agencies would have to cultivate and develop new assets.