Harry Truman was the successor of Roosevelt, the 33rd President of the United States. He served as artillery officer in World War I, making him the only president to have seen combat in World War I. He too has had his share of events, such as the decision to use nuclear weapons on Japan, founding of the United Nations, the Marshall Plan and the Truman Doctrine.
In contrast to Roosevelt, who was more of a patrician, he was a more folksy, unassuming president, popularizing the phrases ‘"the buck stops here" and "If you can't stand the heat, you better get out of the kitchen." During his tenure as president, he was not that popular. But after his retirement from politics, he has gained more favourable assessments, many American historians ranking considering him one of the greatest US presidents.
However, his actions during the Cold War were more aggressive towards the Soviets, compared to that of Roosevelt’s. While Roosevelt believed in Stalin, he was concerned about communism, and containing it. Communist advances in Greece and Turkey led him to policies against them.
However, even so, he managed to get support for both his policies, the Marshall Plan, and the Truman Doctrine.
One event was the letters about the missile bases in Turkey, in the Cuban Missile Crisis.
While deciding to respond to the first letter sent out, and ignoring the second, more aggressive one, Harry Truman was more aggressive about it.
Truman could have been a little less aggressive when handling the Cold war, as his abrasiveness had caused a lot of problems. If he was maybe a little more amiable like Roosevelt, a lot of things could have been averted.
If Roosevelt is considered the peaceful negotiatable side of the US, then Harry Truman is the aggressive hard line side. Truman was very concerned about the spread of communism and came up with many policies to help contain the spread. However, his policies were really aggressive and might have further soured USA-USSR relations. From this, we can say that although Russian aggression might have started the Cold War, the US had a part to play in the worsening of the situation and progression of the Cold War.