What was the Cold War?

The Cold War was an undeclared war of military, economic, and political tensions between the United States and the Soviet Union 

When does the Cold War Begin? What are the dates when the ‘origin’ period occurred?

The Cold War started immediately following the conclusion of WWII to 1947 when both the United States and the Soviet Union attempted to implement specific economic and plans in the process of rebuilding Europe. 

What things did the United States do that alarmed the Soviet Union?

The fact that the United States was the sole owner of nuclear power and they refused to share the technology with the Soviets. We attempted to control as much territory as possible implementing capitalist governments. Along with he transformation of foreign policy that occurred after the death of FDR and the inauguration of Truman.

What things did the Soviet Union do that alarmed the United States?

The Soviet Unions mobilization of military forces into free territories and countries in an attempt to set up puppet communist governments with extreme loyalty to the soviet Union. The backing of communist groups in Turkey, Greece, Czechoslovakia, and several other countries in Europe. Finally, the future aggression pertaining to the Berlin Blockade and the unprovoked invasion of South Korea with soviet backed troops and aid.