It might sound counter-intuitive to outright tell your enemy what you are capable of, but that's exactly how deterrence works. Winning a war is good, but it's better to convince your opponent that they shouldn't start a fight in the first place. Which means your opponent needs to have some understanding of what you are capable of. If they don't, if you develop significant capabilities but keep them secret, your opponent may initiate hostilities with you, under the mistaken assumption that they could win. You don't give them everything, but you give them enough to make them concerned, and even better make them over estimate the size and scale of the threat. Done right, you can get an adversary to devote far more resources to counter your threat than you put into it, or more than is warranted.