The attacks of Sept. 11, 2001 changed American politics forever. But in spite of the warning signs raised by the U.S. intelligence community, the Bush administration seemed preoccupied with other issues, aloof to the alleged threat until the day both towers fell.

Why then, MSNBC’s liberal host Keith Olbermann asked on Friday night, is it “taboo” to blame the Bush administration for allowing the deaths of nearly 3,000 Americans on their watch?

ADVERTISEMENT

His conclusion: For their lack of vigilance and because they “did not prioritize,” President George W. Bush and Vice President Dick Cheney are to be faulted for the attacks.

RELATED: O’Donnell shouts down ‘enhanced interrogation’ defender

Provoked by former Bush and Rumsfeld speechwriter Marc Thiessen’s allegation that President Obama is “inviting” another attack, Olbermann noted that when President Bush was warned by the CIA that terrorists were targeting the United States and may be planning to use airliners, Bush replied, “All right, you’ve covered your ass now” and proceeded to do nothing about it.

Joining him in the discussion was Lawrence O’Donnell, who had been cut off earlier that day by MSNBC’s resident conservative Joe Scarborough in the midst of a tirade in response to Thiessen’s claims.

O’Donnell, an MSNBC political analyst and former chief of staff to the Senate Finance Committee, held nothing back in his second shot at the former speechwriter’s assessment of Bush-era terror politics.

ADVERTISEMENT

“Mr. Thiessen also claimed that torture, which, of course, he will not recognize by that word, saved Los Angeles from its own 9/11,” Olbermann began. “Is this that Liberty Tower, Library Tower, Liberia Tower crap again? Is that what he’s talking about? Is this something else they’ve made up?”

“It’s a very wearisome story that they refused to put away,” O’Donnell began. “It has been debunked time and time again. Timothy Noah on Slate, every time it comes up, he very patiently lays it out again as he did today, that the arrest of the ring leader of this so-called plot occurred the year before the waterboarding occurred of Sheikh Mohammed, and which they now claimed we got the information to stop the plot that had already been stopped. And the FBI has said this is ludicrous, that it did not happen. The FBI doesn’t believe the so-called plot even could have been carried out.”

At the time, intelligence officials attributed the claim of a foiled attack on the Library Tower in Los Angeles — which Bush called the “Liberty Tower” — to political posturing, suggesting it had been nothing more than talk.

ADVERTISEMENT

“The FBI has always thought that this was not a serious threat and whatever it was, was stopped a year before the torture that produced the evidence according to this guy,” O’Donnell said.

“Why is it OK in polite company to say Mr. Obama is inviting attack, but you still can`t say that Mr. Bush not only invited attack but he sent the night watchman home?” Olbermann asked.

ADVERTISEMENT

“Keith, it’s unconscionable to me,” his guest replied. “You know, I mentioned his oath of office to him because I took an oath of office to work in the Senate. It changes your relationship to the institution and to the government. And there are things after that, the places you don’t go. You don’t go to the spot that says this sitting president of the United States is trying to get this country attacked. You don’t go where Dick Cheney went in the 2004 campaign, saying John Kerry would allow an attack. You don’t go to those places. And it is just unconscionable to see someone do it after taking an oath of office to serve this country.”

This video is from MSNBC’s Countdown with Keith Olbermann, broadcast Friday, Feb. 12, 2010.

ADVERTISEMENT

This video is from MSNBC’s Morning Joe, broadcast Friday, Feb. 12, 2010.

Visit msnbc.com for breaking news, world news, and news about the economy