I think that a fairly serious argument can be made that it was political leadership that played a very dominant role in the origins of the cold War. Emerging from the Potsdam Conference, there was noticeable tension between the Soviets and the Americans. Consider the discussion of nuclear weapons. The Soviets, under the leadership of Stalin, reacted "calmly" to the news that the Americans had developed plans to use a nuclear device in the war, knowing full well that the Soviets themselves had started work on their own nuclear device. Both sides failed to seize the opportunity to form an alliance between one another that could have helped to avert an ideological divide between both nations. Consider what might have been had Truman or Stalin suggested a joint effort to control nuclear weapons. The fact that after the bombing of the Japanese, there was little discourse in how a new world order in Japan could represent both American and Soviet interests helped to increase the tension between both nations. This becomes a question of political leadership, with both Stalin and Truman recognizing the potential advantage domestically in defining themselves against the other as opposed to working with "the other." Both sides' reaction to the other represented the fundamental paranoia and fear that would underscore the conflict.
Continuing with this would be how the world was constructed from an ideological point of view following the war. The Americans ended up demonstrating the same level of political inertia to working with the Soviets as they did in working with their capitalist counterparts. The "Long Telegram" by Kennen and the Novikov Telegram both reflect how the political hardline against both nations was being actively advanced by both sets of political leadership. At the insinuation of both hardline approaches, no political repudiation was offered. Both telegrams went very far in advocating that the political leaderships of both nations had little interest in averting tensions between both nations, helping to cause and initate the Cold War. At the same time, Churchill's speech in Missouri about the "Iron Curtain" and its argument that an Anglo- American alliance was the only solution to this threat was never argued or rejected, but rather taken as basic fact. This would be another instance where political leadership helped to cause the Cold War.