d) Teletype Machine

The first direct hotline between the U.S. and Soviet Union, established in 1963 following the Cuban Missile Crisis, utilized a teletype machine. This communication link, known as the “Red Telephone,” was not a telephone in the traditional sense, but a teletypewriter system that allowed for written messages to be directly and quickly exchanged between the White House and the Kremlin. The establishment of this hotline was a significant step towards reducing the risk of accidental nuclear war and improving crisis communication. It symbolized a recognition by both superpowers of the need for reliable and swift communication to manage the high-stakes complexities of the Cold War.