|Fig. 1: The first hydrogen bomb launched by the US on November 1, 1952, code-named "Ivy Mike."  (Source: Wikimedia Commons)|
The race for nuclear supremacy took place right after the end of WWII, when the U.S, Soviet Union, and their other allies began to build an abundance of nuclear weapons. Beginning in WWII, the first nuclear weapon was built by the U.S. and to be used on Nazi Germany and its allies.  Shortly after Joseph Stalin was initially informed of the development of a nuclear weapon in July 1945, the U.S. was ordered to drop two atomic bombs on the Japanese cities of Hiroshima and Nagasaki. The bomb dropped on Hiroshima left 150,000 people killed or wounded, while the bomb dropped on Nagasaki 3 days later left 75,000 people killed or wounded. 
Immediately after WWII, both the US and Soviet Union continued to invest and research nuclear weapons.  While the US developed a strategy called "Operation Crossroads" in which they tested how well nuclear explosions performed on battleships, the Soviet Union constructed a domestic supply of uranium and surprised the world by detonating its first atomic bomb in August 1949.
Both sides continued to fight for world supremacy and began to invest in the creation of hydrogen bombs. [2,3] As shown in Fig. 1, after years of research the US detonated its first hydrogen bomb in November 1942, decimating anything and everything within 100 miles. Several years later, the Soviets subsequently followed with a more dangerous hydrogen bomb. While both sides now had the power to completely wipe out each other, they were limited in how to transport their nuclear weapons. Yet, in the 1950s the Soviet Union and the US began to research intercontinental ballistic missiles, now demonstrating that both sides had the capability of launching a missile and having it target any point in the world. 
Other nations began to follow in the footsteps of the US and USSR. In the 1950s and 1960s, the United Kingdom, France, and China all developed their own nuclear weapons. The increase in nuclear proliferation was beginning to make leaders all around the world feel nervous about future diplomatic relationships - one misstep could cause irreparable damage. 
Following the Cuban Missile Crisis and a series of other problems, nations all around the world started to introduce a series of agreements that would lead to disarmament.  In the 1970s, the US and Soviet Union agreed to a detente, a formal agreement that would limit the amount of money a nation would spend on nuclear power and other weapons. Soon after, the US and USSR agreed to SALT, the Strategic Arms Limitation Treaty, which capped a nation's arsenal of weapons, putting both nations at ease about the amount of nuclear power present in the world. 
As relations between the two superpowers continued to improve into the 1980s, the Soviet Union elected Mikhail Gorbachev to lead the country. Upon election, Gorbachev introduced a series of reforms, many of which attempted to continue to limit the amount of nuclear power each nation had. Several years after, Gorbachev resigned and the Soviet Union dismantled into a series of individual nations.
Following the formal end of the Cold War, most of the nuclear weapons were dismantled or recycled.  Most recently under Obama's administration, the US and Russia agreed to further reduce their strategic nuclear missile launchers, amongst other weapons. Although Trump has outwardly spoken for the need to again strengthen our nuclear arsenal, time will tell whether diplomatic relationships between the US and Russia will strengthen or worsen. 
© Mitchell Kogan. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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 "From the Archive, 13 February 1952: British Consider Sites for First Atomic Bomb Test," The Guardian, 13 Feb 12.