WASHINGTON — The Obama administration said Friday that it would prosecute Khalid Shaikh Mohammed, the self-described mastermind of the Sept. 11 attacks, in a Manhattan federal courtroom, a decision that ignited a sharp political debate but took a step toward resolving one of the most pressing terrorism detention issues.

Attorney General Eric H. Holder Jr. announcing Friday that Khalid Shaikh Mohammed and four others would be tried in federal court in Manhattan.

Is federal court the right place to prosecute the 9/11 defendants?

A photograph taken by the International Committee of the Red Cross of Khalid Shaikh Mohammed this year in Guantánamo Bay, Cuba. The detainee's family released the photo to a Web site,...