Lieberman wants probe into 'terrorist attack' by major on Fort Hood

Homeland Security Chairman Sen. Joe Lieberman (I-Conn.) said Sunday that he intends to launch a congressional investigation into the motives behind "the worst terrorist attack since 9/11" -- the slaying of 13 people at Fort Hood by an Army major who, Lieberman said, reportedly showed signs of being a "self-radicalized, homegrown terrorist."

Reports of Major Nidal Malik Hasan have included statements justifying suicide bombings and shouting "Allahu Akbar!" ("God is great!") at the scene as he went on Thursday's shooting spree, Lieberman noted.

"It's premature to reach conclusions about what motivated him," Lieberman said on "Fox News Sunday," but added that indications range from the major being under personal stress over an impending deployment to various reports that "he had turned to Islamist extremism."

"If that is true, then this was a terrorist act," Lieberman said.

"This is not the first attempt by Islamist extremists to go after U.S. military bases," the senator added, noting foiled plots to attack Fort Dix and Quantico and the shooting death of an Army recruiter in Little Rock, Ark., by a Muslim convert this summer.

There are indications that Hasan supported that act, Lieberman said.

The Homeland Security chairman also urged the Department of Defense to launch an independent investigation "to see if warning signs were missed."

The military, said Lieberman, needs to have "zero tolerance" for those expressing extremist views. "He should have been gone," the senator said.