Hiroshima was bombed because of its military importance to the war. The result of the bombing was 70,000 people killed from initial blast and another 70,000 from radiation.
The United States also dropped an Atomic Bomb on Nagasaki shortly after Hiroshima. Nagasaki was also seen as a military target, resulting in roughly 80,000 casualties.
The bombing of Hiroshima and Nagasaki essentially forced Japan into surrendering, which pretty much ended World War 2.
Executive Order 9835 was signed also known as the "Loyalty Order." This was introduced in order to establish loyalty to the United States. Its main function was to root out communist influences.
The North Atlantic Treaty Organization was designed for The United States, Canada, and several other European nations to give security to each other against the Soviet Union.
The Korean War started because North Korean troops crossed into the 38th Parallel and invaded South Korea.
The Korean War ended when the Korean Armistice agreement was signed. This essentially clearly divided North and South Korea from each other.
The Warsaw Pact was a treaty of friendship between, the Soviet Union, Albania, Bulgaria, Czechoslovakia, and many more nations. It was formed to counteract the NATO
John F. Kennedy was elected as the 35th president of the United States. Kennedy was elected during the Cold War, and pledged to strengthen American military forces.
This treaty prohibits any type of Nuclear Weapon and was the first legally binding international agreement.