In what situation can the U.S. military use nukes without the consent of the President, if any situation like this exists?
Generally, the decision is reserved for the President as Commander in Chief. All other conditions are to assure secure communications and the rule of succession.
- The Vice President can only decide if the President is (temporarily or permanently) unable to decide. The 25th Amendment and the Presidential Succession Act define the order of succession.
- There might be a breakdown of communications which leaves the US military unable to contact the President or his or her lawful successor. In the past, the US president pre-delegated launch authority to the military if certain conditions were fulfilled.
- There is the custom of having a designated survivor away from mass gatherings of the President and most other successors. If something were to happen that kills or incapacitates the President, but leaves a person higher up than the designated survivor alive, then that person higher up is in charge. The designated survivor is just someone in the line of succession who has been briefed and put in touch with strategic communications.
- Today a confirmation of a launch order by a second individual is required. As I understand it, this does not in any way limit the authority of the Commander in Chief, it is merely a procedure to authenticate the integrity of the launch orders.
- There are media reports that during the last days of the Nixon presidency, cabinet officials conspired to take the solitary launch ability away from the President. That was arguably
treasoncriminal, but push never came to shove.