BY SPENCER ACKERMAN

The man in charge of America’s drone wars will face Senate questioning about perhaps their most controversial aspect: when the president can target American citizens for death.

Daryl Johnson had a sinking feeling when he started seeing TV reports on Sunday about a shooting in a Wisconsin temple. “I told my wife, ‘This is likely a hate crime perpetrated by a white supremacist who may have had military experience,’” Johnson recalls.

An internal FBI investigation into its counterterrorism training has purged hundreds of bureau documents of instructional material about Muslims, some of which characterized them as prone to violence or terrorism.

The White House quietly ordered a widespread review of government counterterrorism training materials last month, following Danger Room’s reports that officials at the FBI, military and Justice Department taught their colleagues that “mainstream” Muslims embrace violence and compared the Islamic religion to the Death Star.

The FBI wasn’t just wrong in teaching its agents that average Muslims are likely to be terrorist sympathizers, Attorney General Eric Holder told Congress Tuesday. That bigoted Bureau training undermined the government’s efforts to stop the next terror attack.

Following months of denials, the FBI is now promising a “comprehensive review of all training and reference materials” after Danger Room revealed a series of Bureau presentations that tarred average Muslims as “radical” and “violent.”

The FBI has publicly declared that its counterterrorism training seminars linking “mainstream” Muslims to terrorists was a “one time only” affair that began and ended in April 2011.

The FBI is teaching its counterterrorism agents that “main stream” [sic] American Muslims are likely to be terrorist sympathizers; that the Prophet Mohammed was a “cult leader”; and that the Islamic practice of giving charity is no more than a “funding mechanism for combat.”