The essence of the Cold War was the rivalry of the two systems in the ideological and economic spheres, the struggle for influence on the Third World countries, the increase of nuclear, chemical, bacteriological weapons of mass destruction, all kinds of conventional weapons, the increase in the number of armies, and so on. The reasons for the Cold War were multiple, and it is difficult to find out which side was responsible for the war.
The Cold War began when differences in post-war worldviews raised suspicion and mistrust between the US and the USSR. The first conflict occurred around Poland. The Cold War began with public statements. In 1946, Stalin declared the impossibility of peace in the world "under the conditions of modern capitalist development of the world economy" (Waltz). Winston Churchill, Prime Minister of Great Britain during the war, gave a famously spectacular speech in Fulton, Missouri. According to him, "from the Szczecin in the Baltic to Trieste on the Adriatic, an iron curtain was sleeping on the continent"; Churchill stressed that Britain and the United States need to go side-by-side to counter the Soviet threat.
The ideological confrontation between the USSR and the countries of the West, which subsequently manifested itself in concrete actions in the international arena, led to the Cold War. The division of the world took place through the economic and political integration of developing countries in Western European political and economic models and countries of socialism, the landmark for which was the totalitarian Soviet Union (Lebow).
The Cold War has led to a prolonged, exhausting arms race for the economy. At the same time, the Western powers, with their powerful industrial potential, advanced technologies, and flexible market economy, we're in a better situation than the USSR and its allies. So, it is difficult to say which side was responsible for the Cold War, but it is fair to say that both sides acted in a way that led to the conflict.