After the war in Europe was over, cities lay in ruins due to the aerial bombing and battles that had caused widespread destruction.  It was decided at the Yalta Conference that parts of Germany would be given to Poland while the rest of it would be divided into four parts. Berlin, the capital of Germany was also divided into four occupation zones. Berlin and Germany were to be occupied by the French, British, Americans and Russians in their respective occupation zones. East Germany, which was ruled by communist Russia, was separated by the Berlin Wall from independent West Germany, thus giving a physical meaning to Churchill's "iron curtain" that existed between the East and West.

The war in the Pacific ended when Japan surrendered following the atomic bombing of Hiroshima and Nagasaki.  Truman's rationale for using these catastrophic devices was to prevent the greater number of deaths that would occur if the US were to invade the Japanese mainland.  Fortunately, his decision did bring about the end of the war.  Unfortunately, this also opened up a more dangerous can of worms: the nuclear arms race.

While the US and Soviet Union emerged as the two most powerful nations on earth, opposing national interests would usher in the Cold War era that would last until the late 1980's.  By the time of the signing of the Axis satellite treaties early in 1947, the two countries were drawing apart. Before long, the Soviets had built and tested their own nuclear devices, which served to increase tensions between the two nations, drawing them even further apart.  

Fearing the spread of communism, the US committed troops to suppress communist governments in various hotspots worldwide.  This "policy of containment" soon dominated the United States' attitude towards foreign affairs, even if it led to corrupt dictators gaining power or supporting weak, non-communist governments.  Meanwhile, those back in the US weren't immune from this policy either, as fear of communist infiltration (or the "red scare") swept the nation. Later, civil unrest would erupt once again in protest of the Vietnam War and life back in the states.  

Meanwhile, the cold war pushed on. 

Hoping to gain the upper hand in defending their home soil, both the US and the Soviets aimed nuclear-warhead-tipped ICBM's at the other's major cities and industrial areas.  These missiles could be launched at a moments notice, meaning immediate retaliation for any warranted or unwarranted aggression.  Worse yet, these missiles could not be retrieved once fired, meaning that a simple mistake could lead to nuclear war.

Only this fear of imminent retaliation and total annihilation would keep these two superpowers from using their nuclear arsenals on one another.

But in the meantime, no place on earth would be safe.

Luckily, we now know that the world would survive, but needless to say, it was a powerful threat and worrisome burden on those who had to live during this fragile time period.  In fact, the entire world depended on it!

*Conclusion*