United States wildland fire policy and program reviews in 1995 and 2000 required both the reduction of hazardous fuel and recognition of fire as a natural process. Despite the fact that existing policy permits managing natural ignitions to meet resource benefits, or Wildland Fire Use (WFU), most fuel reduction projects rely on mechanical treatments and prescribed fire. Budget constraints suggest that successful fuel and ecosystem management hinges on expanding WFU. The decision to authorise WFU in the US Department of Agriculture Forest Service (USFS) rests with line officers, and the so-called 'go/no go' decision constitutes a time-critical risk assessment. Factors influencing this decision clearly impact the viability of WFU. The present study examined influences on line officers' go/no go decision. A telephone survey was conducted of all USFS district rangers with WFU authority in the Northern, Intermountain, and Southwestern Regions. The census was completed during February 2005 and obtained an 85% response rate. Data were analysed using Classification and Regression Tree analysis. Personal commitment to WFU provided the primary classifier for 91% of the district rangers who authorized WFU. External factors, negative public perception, resource availability, and a perceived lack of support from the USFS were the main disincentives to authorizing WFU.