Who is John McCone from Thirteen Days; a Memoir of the Cuban Missile Crisis and what is their importance?

The Director of the Central Intelligence Agency (CIA) in the Kennedy Administration, McCone lets JFK get a good night's sleep on the night of October 15, 1962, after being advised of Soviet missiles in Cuba. McCone and the CIA are primarily responsible for Ex Comm being kept abreast of breaking news. McCone warns how well equipped the enemy is and conditions in Cuba are as adverse as in Korea.