Why do we announce this? I can’t think of a single reason if it isn’t just a bluff. “Loose lips sink ships” has been given a new definition here.
The enemy will find out anyway whether it's announced or not. That said, announcing it makes him expend resources on countermeasures if it's nothing more than thinking about the threat. Just something else to keep him up at night.
“Why do we announce this?”
Defense contractor stock manipulation.