The Bulletin was created in 1945 by University of Chicago scientists who had worked on the creation of nuclear weapons. In an effort to point towards the danger to which humanity was exposed the clock was created as a sign. For the past 70 years the position of the minute hand has varied. It was set at 17 minutes to midnight following the signing of the Strategic Arms Reduction Treaty in 1991, which was seen as a very hopeful event. Other events, such as the testing of nuclear weapons by North Korea have seen the hand move closer to midnight.
The clock has never been closer than two minutes to midnight. The clock was first set to two minutes following the initial testing of Thermonuclear Weapons by the United States and the Soviet Union in 1953. Until the present the clock has not been so close to doom since the height of the Cold War.
According to the Bulletin:The greatest risks last year arose in the nuclear realm. North Korea’s nuclear weapons program made remarkable progress in 2017, increasing risks to North Korea itself, other countries in the region, and the United States. Hyperbolic rhetoric and provocative actions by both sides have increased the possibility of nuclear war by accident or miscalculation.
They went on to say:... there has also been a breakdown in the international order that has been dangerously exacerbated by recent US actions. In 2017, the United States backed away from its long-standing leadership role in the world, reducing its commitment to seek common ground and undermining the overall effort toward solving pressing global governance challenges. Neither allies nor adversaries have been able to reliably predict US actions—or understand when US pronouncements are real, and when they are mere rhetoric. International diplomacy has been reduced to name-calling, giving it a surreal sense of unreality that makes the world security situation ever more threatening.
Lest we forget, the United States possesses at least one thousand four hundred thermonuclear weapons which are less than an hour away from any target which might be chosen. Russia holds similar numbers of weapons, while Britain, China, France, India, Israel, North Korea, and Pakistan also hold deliverable weapons.https://thebulletin.org/2018-doomsday-clock-statement