The origins of the Cold War can be traced back to several pivotal events and ideological conflicts between the USSR and the US. The emergence of the USSR as a nuclear power and the rise of Communist China significantly bolstered Soviet morale while alarming the US.
US saw this as a threat, this combined with China becoming communist was a huge morale boost to the USSR
China becomes Communist
Mao Zedong becomes leader of the communist party of China, offering big morale boost for USSR in combination with getting atomic bomb.
Berlin Blockade
US wanted to help unify the economy of the East and West Germany, but USSR saw this as a breach of the Potsdam - the treaty that they opposed in the first place. Essentially, the USSR was feeling super threatened and like the Western Allies were just out to get them
Marshal Plan (48-51)
US offered to help rebuild all of the WWII countries, including the USSR, but doing so would link them inextricably with the US's economy, effectively preventing communism from heading there
Truman Doctrine (1947)
US explicitly states that they would like to contain communism, offering to fund anybody who is "threatened" by it
UN being led by US
The USSR saw this as a threat, and were worried that the UN would become a congregation of communist hating pigs
Yalta and Potsdam conferences
Didn't exactly give the USSR what they wanted as far as post war goals went
Allied hesitation to assist USSR in WWII
Instead of immediately coming to their aid, the US decided to take the long route through Africa and Italy, making Russia suffer a great number more losses between 1941-1945 than they could have. USSR saw this as the US trying to bleed them out so capitalism could win. They weren't entirely off base, but the US was just trying to not kill all their men which should be commended.
Rival ideologies
The red arrow is the time flow
The heavily communist USSR was intent on not letting the heavily capitalist US take advantage of them. After the Russian Revolution in 1917, when the USSR became communist, the U.S.A.'s all-seeing eye turned to them because of the threat they posed to the market economy and to the free government. They were opposed even when they didn't know it.
