American extended deterrence commitments span the globe. Despite extensive research on the causes of deterrence successes and failures, evidence of which US allies find what extended deterrence commitments credible is elusive. This article utilizes interviews with former Australian policy-makers to analyze the credibility of the United States to defend Australian forces during the 1999 INTERFET intervention in East Timor. While there was no direct threat to Australian sovereignty, the episode stoked concerns in Canberra regarding the willingness of Washington to come to Australia's assistance. The Howard government coveted a US tripwire force presence, and the Clinton administration's unwillingness to provide this raised serious concerns among Australian political elites about the alliance. While this says little about the separate question of whether Washington would use nuclear or conventional weapons in defense of Australian sovereignty, the Timor case indicates the existence of an extended deterrence credibility deficit regarding the more probable low-intensity conflicts that Australia finds itself in.