The site here is the National Military Command Center at the Pentagon.  The president would need to interact with them if he used the nuclear football for an attack.

The nuclear football (also known as the atomic football, the president's emergency satchel, the button, the black box, or just the football) is a briefcase, the contents of which are to be used by the President of the United States to authorize a nuclear attack while away from fixed command centers, such as the White House Situation Room. It functions as a mobile hub in the strategic defense system of the United States.

• http://en.wikipedia.org/wiki/Nuclear football