"I think that's a very valid concern. And as I have pointed out, I think this is a very unusual occassion," Mueller said.
"We have undertaken a review from top to bottom of our counterterrorism training. I think these are isolated incidents," Mueller said. "We have 34,000 employees and we do a great deal of training. We understand the sensitivity and the importance of assuring that that training that we give to our persons are appropriate."
The FBI, facing pressure from Muslim groups after the revelation of the training materials by Wired reporter Spencer Ackerman, said they had taken steps to prevent such material from leaking into their training programs in the future.
But Ackerman has since uncovered new evidence of Justice Department employees casting Islam as an existential threat to the United States. An "intelligence specialist" who worked for the U.S. Attorney's office in the Middle District of Pennsylvania warned in a 2010 Power Point presentation of a "Civilizational Jihad" conducted by "civilians, juries, lawyers, media, academia and charities." Earlier this year, a FBI trainer compared Islam to the "Death Star."
In his testimony, Mueller defended the FBI's relationship with the Muslim community, saying that all of the FBI's 56 field offices have worked on those relationships in the years since the Sept. 11 attacks.
"Our outreach over the years has been very successful I think in bridging the relationships with the Muslim-American community, and this is I think something that's unfortunate and we've addressed it," Mueller said.
Excerpts from Mueller's testimony: