The Muslim Brotherhood operates behind the scenes in the United States and seeks to subtly place individuals into influential positions in the academic, legal or medical professions to further their cause of undermining the United States.
So far all investigations of Hasan have indicated that he acted alone, without support or direction from any outside group. Stories published this week indicated that Hasan had been in contact with al Qaeda, but further reporting revealed that Hasan had only been in contact with, who had expressed support for al Qaeda - and that Hasan had approached the cleric with questions for a research paper.
Investigators are now also looking at whether Hasan was supporting Islamic charities overseas. Some such charities have been found to funnel money to terrorist organizations.
Earlier Thursday, President Barack Obama hasrelated to Fort Hood shooting suspect Maj. Nidal Malik Hasan, and whether the information was properly shared and acted upon within government agencies.
The review will be overseen by John Brennan, assistant to the president for homeland security and counterterrorism. The first results are due to the White House by Nov. 30.
More Coverage of the Tragedy at Fort Hood:
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Army Doctors Had Doubts over Hasan
Exclusive: Inside Hasan's Apartment
Fort Hood Hero Recalls "Chaotic" Scene
The Government Blame Game
Ft. Hood Shooting: Composure Under Fire
Radical Imam's Web Site Praises Hasan
List of Fort Hood Dead, Wounded