It’s the suitcase nuke that makes the ultimate nightmare scenario. The Russians wouldn’t have to launch missiles from land or sub. Vaporize Congress, the White House (and the ‘football’), and the Pentagon with a suitcase, and they could launch the rest of their stuff at their leisure without fear of retaliation. Without the codes, the subs couldn’t launch their stuff.
There are three such “footballs” in existence. The first travels with the President, a spare is kept at the White House, and the third is with the Vice President. Anyways, the missiles would still be launched by the commander of National Military Command Center and multiple airborne command posts .
National Military Command Center is responsible for the emergency action messages that are relayed to the submarines to launch their missiles.