The worst terrorist attack in U.S. history represented one of its greatest leadership challenges, and the decisions made on that day still reverberate 25 years later.

President George W. Bush was elected in the contentious 2000 election largely on a domestic-focused platform. The Sept. 11 terrorist attacks were an unexpected test for his new administration, only nine months old at the time. Several of the key figures in the administration remain well-known, for better or worse, while others have faded into relative obscurity.