Who started the Cold War? How historians still disagree

There is no agreed answer, and the disagreement has a history of its own. Historians have sharply disagreed about who was responsible for the breakdown of Soviet–US relations after World War II and about whether the conflict was inevitable. They commonly speak of three approaches: "orthodox," "revisionism" and "post-revisionism."

The orthodox school, the first to emerge in the US, places responsibility on the Soviet Union and its expansion into Eastern Europe. Thomas Bailey, for example, argued in 1950 that Stalin violated promises made at Yalta, imposed Soviet-dominated regimes on unwilling populations and conspired to spread communism. Soviet historiography, meanwhile, was overwhelmingly dictated by the Soviet state and blamed the West.

Revisionists answered that Americans had always been an empire-building people, that American policymakers wanted to maintain the market system through an "open door" policy, and that the Soviet occupation of Eastern Europe had a defensive rationale. Post-revisionists accepted some revisionist findings but rejected most of their key claims, and since the 2000s historians have moved on from questions of blame and inevitability.