Asimov used this idea in his excellent short story "Spell My Name with an S" from 1958.
Dr. Kristow said stolidly, "Executed!" "He might have been. Ordinarily, I would even assume so, though the Russians are not more foolish than we are and don't kill any nuclear physicist they can avoid killing. The thing is there's another reason why a nuclear physicist, of all people, might suddenly disappear. I don't have to tell you." "Crash research; top secret. I take it that's what you mean. Do you believe that's it?"
[...]
"Has it been decided that we're to go on shield research, too?" "Yes." Kristow's hand went back over his short, bristly hair, making a dry, whispery sound. "We're going to give it everything we've got. Knowing the papers written by the men who disappeared, we can get right on their heels. We may even beat them to it. —Of course, they'll find out we're working on it." "Let them," said Brand. "Let them. It will keep them from attacking. I don't see any percentage in selling ten of our cities just to get ten of theirs— if we're both protected and they're too dumb to know that." "But not too soon. We don't want them finding out too soon.
Dr. Kristow said stolidly, "Executed!" "He might have been. Ordinarily, I would even assume so, though the Russians are not more foolish than we are and don't kill any nuclear physicist they can avoid killing. The thing is there's another reason why a nuclear physicist, of all people, might suddenly disappear. I don't have to tell you." "Crash research; top secret. I take it that's what you mean. Do you believe that's it?"
[...]
"Has it been decided that we're to go on shield research, too?" "Yes." Kristow's hand went back over his short, bristly hair, making a dry, whispery sound. "We're going to give it everything we've got. Knowing the papers written by the men who disappeared, we can get right on their heels. We may even beat them to it. —Of course, they'll find out we're working on it." "Let them," said Brand. "Let them. It will keep them from attacking. I don't see any percentage in selling ten of our cities just to get ten of theirs— if we're both protected and they're too dumb to know that." "But not too soon. We don't want them finding out too soon.