Examining voices from Australia’s radical left, this article explores how opposition to the United States’ military and economic presence in Australia was expressed from the late 1940s to the mid-1960s. Responding to Australia’s security and trade relationships with the United States, critics such as the Communist Party of Australia and its associated peace organisations alleged that a US alliance would compromise Australian security in a nuclear-armed world. By looking at the variety of ideas espoused by Australians who questioned the security of a ‘peace’ offered by Australia’s most powerful ally, this paper argues that this evolving language of dissent demonstrates deeper currents of anxiety about Australia’s place in the Cold War world.