Final answer:
Stalin likely would have responded to Churchill's Iron Curtain Speech with strong criticism, positioning the USSR as a protective force against Western capitalism and reasserting the moral high ground of communism.
Step-by-step explanation:
If Joseph Stalin were to respond to Winston Churchill's Iron Curtain Speech, it is likely that he would be highly critical and view it as a direct attack on the Soviet Union and its intentions in post-war Europe. Considering Stalin's reaction to events and criticisms in the past, particularly in light of his commitment to communism and its spread as evidenced in his own speeches, he would perceive Churchill's words as threatening and part of Western propaganda against the USSR. Stalin's speech in February 1946 was an attack on capitalism, where he declared peace impossible under such a system, asserting the supremacy of communism.
Post-war, Stalin was portrayed as being in a state of prostration, showing little interest or initiative in response to political upheavals or protests. This reaction might have been different in the case of a direct challenge, like Churchill's speech, which contradicted the Soviet narrative and positioned the USSR as an oppressive force. Furthermore, historical accounts show that after the American-Soviet Conflict and Churchill's speech, Stalin reconsidered his plans for retirement and continued his leadership, likely galvanized by the need to respond to the challenge posed by the West.
Considering Khrushchev's later responses to Western criticism which reinforced Soviet stances against the US, it is conceivable that Stalin would also have responded with strong rhetoric and recommitment to the communist cause, asserting the Soviet Union's role as a defender of Eastern Europe against capitalist encroachment. Stalin, a figure of public scarcity, would likely use his response as yet another historical milestone to assert the USSR's moral high ground over the West.