Monroe didnít want a European power who later will make a European colonies in America. Colombia and Argentina ,gaining their independence, were examples for other countries as self-rule.
So in this case Monroe asked J.Q. Adams to write a foreign policy statement, or a doctrine. The resulting document was called later THE MONROE DOCTRINE, who contained 4 important points for the independence of America and the independence of the colonies:1-Any European countries could no longer establish colonies in the North or South America;2-The political systems of the Americanís states will be separate from those of Europe;3-Any European attempt to influence the American justice or political administration will be considerate as a threat to the peace and to the safety of American states;4-The US government would not interfere with the European governments or their colonies.
Since 1823, the year when the Monroe Doctrine was write and proclaimed, it was a very important document for the American legislation and for American relations with other states. JOHN F. KENNEDY:
Although the Second World War was over in 1945, 2 big powerful nations, US and Soviet Union(SU), continued to develop many and powerful weapons for mass destruction.
In 1952-1953 those 2 nations tested their first H-bombs(hydrogen-bombs), who are many times more destructive then a regular atomic bomb. If they were using those H-bombs they were capable to destroy each other.
To the end 1950s they had so many nuclear missiles that they could kill everybody on earth.
It was ,between 2 powers , a balance of terror with so many nuclear weapons. If one of 2 nations started a war between them neither of them could win it , because they had an equal quantity of weapons.
Because of this , Eisenhower and Khrushchev wanted to bury the axe of war. So in may 1960 the 2 of them were on they way to a summit in Paris when a US spy plane was shot down when it was making photos to the military installation in SU. This act put an end to the talks before they had even started.
After that incident, the next president of US was JFK, from 1961.In this period he was faced with the crisis in Cuba. Fidel Castro seized power in 1959, and nationalized the American assets and installed a communist government.