During the Cuban Missile Crisis, President Kennedy and Soviet Premier Khrushchev communicated by encrypted messages that had to be relayed by telegraph or radioed between the Kremlin and the Pentagon. JFK feared this was too cumbersone and not effective in a crisis
The new Washington-Moscow hotline enabled presidents to call the Pentagon with a message, which would be immediately typed into a teletype machine and fed into a transmitter. The message could reach Moscow in minutes, as opposed to hours. In 1963, it was regarded as a marvel