If I remember correctly, Eric Schlosser's Command and Control recounts an incident where an American nuclear missile crew were erroneously given the order to fire a nuclear missile at the Soviet Union. The person at the other end of the phone had simply read them the incorrect code, intending to give a routine instruction related to maintenance. Launch codes were validated, and by the procedure the missile should have been launched.
Thinking that this was likely an error due to the officer's tone of voice and the present geopolitical situation, the missile crew asked him to repeat the order, and he cheerfully repeated the code for firing the missile. Only after being prompted for a third time did he realize his mistake and relayed the correct encrypted order. The near-accident was not reported at the time.
The article mentioned that the crews started their 24 hour shift with top-secret security briefing on the world situation.
Considering cases like this, it was probably quite good idea to share the information with the crew so that they could make more educated decisions instead of just blindly obeying orders.
Thinking that this was likely an error due to the officer's tone of voice and the present geopolitical situation, the missile crew asked him to repeat the order, and he cheerfully repeated the code for firing the missile. Only after being prompted for a third time did he realize his mistake and relayed the correct encrypted order. The near-accident was not reported at the time.