ht||Time||Change||Reason|
|1947||7||23:53||—||The initial setting of the Doomsday Clock.|
|1949||3||23:57||-4||The Soviet Union tests its first atomic bomb, officially starting the nuclear arms race.|
|1953||2||23:58||-1||The United States and the Soviet Union test thermonuclear devices within nine months of one another. (This is the clock's closest approach to midnight since its inception.)|
|1960||7||23:53||+5||In response to a perception of increased scientific cooperation and public understanding of the dangers of nuclear weapons (as well as political actions taken to avoid "massive retaliation") the United States and Soviet Union cooperate and avoid direct confrontation in regional conflicts such as the 1956 Suez Crisis. Scientists from different countries help establish the International Geophysical Year, a series of coordinated, worldwide scientific observations between nations allied with both the United States and the Soviet Union, and the Pugwash Conferences on Science and World Affairs, which allow Soviet and American scientists to interact.|
|1963||12||23:48||+5||The United States and Soviet Union sign the Partial Test Ban Treaty, limiting atmospheric nuclear testing.|
|1968||7||23:53||-5||Regional wars wage: Vietnam War intensifies, Six-Day War occurs in 1967 and Indo-Pakistani War of 1965 takes place. Worse yet, France and China, two nations which have not signed the Partial Test Ban Treaty, acquire and test nuclear weapons (the 1960 Gerboise Bleue nuclear test and 1964 596 nuclear test, respectively) to assert themselves as global players in the nuclear arms race.|
|1969||10||23:50||+3||Every nation of the world, with the notable exceptions of India, Pakistan, and Israel, signs the Nuclear Non-Proliferation Treaty.|
|1972||12||23:48||+2||The United States and the Soviet Union sign the SALT I (Strategic Arms Limitation Treaty) and the Anti-Ballistic Missile Treaty.|
|1974||9||23:51||-3||India tests a nuclear device (Smiling Buddha), SALT II talks stall. Both the United States and the Soviet Union modernize MIRVs.|
|1980||7||23:53||-2||Unforeseeable end to deadlock in American–Soviet talks as Soviet war in Afghanistan proceeds. As a result of the war, the U.S. Senate refuses to ratify SALT II agreement between both nations and President Jimmy Carter pulls the United States from the 1980 Summer Olympic Games in Moscow and considers ways in which the United States could win a nuclear war.|
|1981||4||23:56||-3||The clock is adjusted in early 1981. Soviet war in Afghanistan toughens the U.S. nuclear posture. Ronald Reagan becomes president, scraps further arms reduction talks with the Soviet Union and argues that the only way to end the Cold War is to win it. Tensions between the United States and the Soviet Union contributes to the danger of the nuclear annihilation.|
|1984||3||23:57||-1||Further escalation of the tensions between the United States and the Soviet Union. The clock is adjusted in December 1983 since the ongoing Afghanistan war heats the Cold war. U.S. Pershing II medium-range ballistic missile and cruise missiles are deployed in Western Europe. Ronald Reagan pushes to win the Cold War by intensifying the arms race between the superpowers.|
|1988||6||23:54||+3||In December 1987 the Clock is moved back as the United States and the Soviet Union sign treaty to eliminate intermediate-range nuclear missiles, and their relations improve.|
|1990||10||23:50||+4||Fall of the Berlin Wall, dissolution of Iron Curtain, Cold War nearing an end.|
|1991||17||23:43||+7||United States and Soviet Union sign the Strategic Arms Reduction Treaty, the Soviet Union dissolves. (This is the furthest from midnight the clock has been since its inception.)|
|1995||14||23:46||-3||Global military spending continues at Cold War levels; concerns about post-Soviet nuclear proliferation of weapons and brainpower.|
|1998||9||23:51||-5||Both India (Pokhran-II) and Pakistan (Chagai-I) test nuclear weapons in a tit-for-tat show of aggression; the United States and Russia run into difficulties in further reducing stockpiles.|
|2002||7|