The USSR’s actions in 1945-46 was definitely more aggressive than the US’. One example included Stalin’s breaking of the agreements he had made with Roosevelt at Yalta about the holding of free and fair elections in Eastern Europe after the end of WWII. Stalin’s actions reinforced the legitimacy of the Riga Axioms that the USSR was inherently aggressive and cannot be negotiated with, which then provoked a US response of aggression in 1947. The USSR’s continued military presence in Eastern Europe, alongside the pressing of Turkey and Iran for territorial concessions that will have extended Soviet influence, all contributed to the perception that they were expansionistic and thus aggressive. It can be argued that the USSR had legitimate reasons for expansion, to avoid a repeat of the German invasion in WWII, and thus their actions cannot be considered aggressive. But with the collapse of the USSR, the opening up of Soviet archives provided new evidences to support the traditionalist view that Stalin had imperial ambitions driven out of ideology and own paranoia. Since it is clear now that Stalin had the intent, which is more than can be said of the US, the USSR was more aggressive in 1945-46 and provoked the US into a response, thus deserving more responsibility.
US actions in 1945-46, on the other hand, were definitely less aggressive than the USSR because they lacked the intent for aggression. The abrupt end of the Land Lease Aid with the end of the war was looked upon less than favourably by the USSR, and was seen as an act of aggression. But the US did not intend it to be so; to them, the Land Lease Aid was a form of wartime assistance, to be terminated upon the end of the war. The delay in the opening of the second front during WWII was seen by the USSR as a deliberate act of aggression, with the consequence being Soviet forces being forced to bear the full weight of the German onslaught for a longer period of time. But it can be argued the Americans were merely being concerned for the welfare and lives of their own soldiers, for which they were definitely accountable to the American people, something that Stalin was foreign to. The US had every intention of brokering a peaceful post-war relationship with the USSR, as Truman was influenced by the American people’s desire for peace, until aggressive actions by the USSR like the aforementioned as well as the outrageous demands that Molotov made at the CFM in Moscow led to the US to review their foreign policy towards the USSR. The Long Telegram and Article X were thus written as a result.
As a result of the Long Telegram and Article X, it can thus be seen that US actions from 1946-49 were more aggressive. With the aforementioned reports by Kennan banishing any notions of brokering peace with the USSR, the Americans themselves adopted a non-compromising stance. The Truman Doctrine in 1947 outlined the US’ commitment to a long-term containment of communism and the USSR. The Marshall Plan, the economic arm of the Truman Doctrine, divided Europe into 2 blocs: those receiving Marshall aid, and those not. The Marshall Plan was also designed to save Western European countries from economic ruin and thus communism. The division of Germany also became permanent, with the creation of Bizonia in 1947. It was because of these measures by the US that provoked the USSR into an aggressive response, with the formation of COMINFORM, the post-war version of COMINTERN, the Molotov Plan, the Soviet response to the Marshall Plan, as well as the formation East Germany in 1949, a response to the formation of West Germany. The USSR also accelerated the Sovietisation of Eastern Europe after the implementation of the Marshall Plan by the US. The increasing affluence of Bizonia and the creation of the Deutschmark in 1948 also led Stalin to impose the Berlin Blockade, which spectacularly failed. The Berlin Blockade then led to the formation of NATO, consolidating Europe’s split into 2 camps.
In conclusion, it can be seen how initial and intended Soviet aggression in 1945 led the US to change its pacifist stance in 1946 to an equally aggressive one in 1947 through the Truman Doctrine. Stalin’s imperialistic ambitions were fuelled partly by ideology and partly by insecurity, and it can be seen how his perception of the world influenced Truman’s worldview to change and follow suit. With Stalin being the provocateur as well as the man with the expansionistic ambitions, it can thus be seen how the USSR was more aggressive in 1945-46, leading to equal American aggression in 1947-48, and thus the USSR should be more responsible for the outbreak of the Cold War, reflecting the Post-post revisionist school of thought.