Which incident is most closely related to the installation of the "hot line" between the soviet union and the united states?

The Cuban Missile Crisis of October is 1962 was the inspiration behind the hot line between the United States and Soviet Union. The Cuban Missile Crisis was a result of the US having missiles in Turkey and the Soviet Union having missiles in Cuba. This incident was the closest the world has ever come to all out nuclear warfare. The tense negotiations that took place of these 13 days in October made the government realize that they needed direct access to the Soviet government, as many of the interactions between the US and Soviet Union took a significant amount of time.