During the early Cold War, Vennberg was an adherent of the so-called "third stance" () in Swedish public debate, which advocated a neutral stance in the conflict between the two superpowers. Despite this, he participated in a gathering at the USSR embassy in Stockholm where he praised the "cultural upbuilding" in the USSR. In 1948, he participated in the World Congress of Intellectuals for Peace in Wrocław, Poland, where he was elected to the International Committee of Intellectuals in Defence of Peace.
