This article addresses the question of how US extended nuclear deterrence might endure in a shifting Asia-Pacific where the traditional nuclear order underpinning the credibility of US security guarantees is deteriorating. The Australian case study demonstrates how periods of nuclear order and disorder can inform a state's attitudes toward the credibility of extended nuclear deterrence. Australia's interest in a nuclear weapons capability from 1956 to 1972 was symptomatic of a period of nuclear disorder. This interest declined from the early 1970s due to changes in both the global and regional environments where the proliferation and use of nuclear weapons was relatively contained. This emerging, recognizable nuclear order diminished the interest in an indigenous nuclear weapons capability and led Canberra to rely on US extended nuclear deterrence. This order has remained fairly robust for more than 30 years. However, beyond 2012, we may yet witness a breakdown in this order. This will generate a much greater interest by US allies in the operational aspects of US extended nuclear deterrence.