Every president since John F. Kennedy has a “football,” the briefcase that helps identify a president in order to verify a military engagement. The football “idea” came about during the Eisenhower administration and implemented after the Cuban Missile Crisis that tested the mettle of Kennedy and Khrushchev. The first version combined fashion with security, a slim zero-halliburton case covered in soft black leather with a wristband that connected the wearer by cord to the briefcase handle. Today’s version is considerably wider and without the semblance of security a cord gives, but the black leather remains.
Have a look at the Smithsonian story about the bag known officially as the “president’s emergency satchel.”