Could the Fort Hood Shootings Have Been Prevented?

President Obama attended services at Fort Hood today for the 13 victims of last week's shootings. Major Nidal Hasan is recovering from his own wounds and has yet to be charged. In the meantime, it's reported that the FBI and Army intelligence investigated contacts between the alleged shooter and a militant Islamist cleric who is calling him "a hero." Why did the FBI and the Army decide not to pursue his contacts the cleric? Did they know that Hasan warned fellow officers that Muslim soldiers could be dangerous because of conflicts about fighting in Muslim countries? Is al Qaeda telling Muslim soldiers to commit violence? Do they face discrimination, especially where Christian fundamentalism is widespread?