LIEBERMAN IGNORES CASEY’S ADVICE…. Gen. George Casey, the Army’s Chief of Staff, appeared on CNN yesterday to talk about last week’s shootings at Fort Hood. Not surprisingly, Casey said he couldn’t “speak to the particulars of the investigation or to any motivation” Maj. Nadal Malik Hasan may have had.

It’s worth noting, though, that Casey urged caution. “We have to be careful,” Casey said, “because we can’t jump to conclusions now based on little snippets of information that have come out.” The general added that speculation could “cause a backlash against some of our Muslim soldiers.”

That’s obviously a responsible position to take. Military officials are already conducting an investigation; there’s every reason to be confident that they’ll conduct a thorough probe; and it would be a mistake to jump to conclusions based on limited information.

And then there’s Senate Homeland Security and Government Affairs Committee Chairman Joe Lieberman (I-Conn.) — who’s suddenly discovered his desire to use his committee gavel, and who has no qualms about speculating publicly.

A senior U.S. senator on Sunday said the shootings at Fort Hood could have been a terrorist attack, and that he would launch a congressional investigation into whether the U.S. military could have prevented it.

Sen. Joe Lieberman … said initial evidence suggested that the alleged shooter, Army Major Nidal Hasan, was a “self-radicalized, home-grown terrorist” who had turned to Islamic extremism while under personal stress. […]

Mr. Lieberman said that if news reports were true that Mr. Hasan had turned to Islamic extremism, “the murder of these 13 people was a terrorist act and, in fact, it was the most-destructive terrorist act to be committed on American soil since 9/11.”

“We don’t know enough to say now, but there are very, very strong warning signs here that Dr. Hasan had become an Islamist extremist and, therefore, that this was a terrorist act,” Mr. Lieberman added.

At one point in the interview, Lieberman said it’s “premature to reach conclusions about what motivated” Hasan, and then spent several minutes speculating about the massacre, the gunman, and possible terrorist motivations.

Perhaps the senator is confused. If Lieberman prefaces his remarks by saying things like “we don’t know enough to say” and “it’s premature to reach conclusions,” it doesn’t give him license to then make a series of unproven allegations and speculate wildly on national television.

Gen. Casey told George Stephanopoulos, “We all want to know what happened and what motivated the suspect, but we need to … let the investigation take its course.” Casey probably wasn’t addressing Lieberman directly, but he might as well have been.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.