Cheney's statement, "Simply stated, there is no doubt that Saddam Hussein now has weapons of mass destruction." indicates certainty.
None of the reliable evidence indicated certainty. Even the October '02 NIE contained caveats. Bush could not say truthfully and with certainty that Saddam Hussein had WMD, and yet he did. He lied.
Both Colin Powell in February 2001, and Condoleezza Rice in July 2001 stated in no uncertain terms that Saddam Hussein was not a threat
Furthermore, Bush et al made the decision to go to war (apparently without evidence of any kind) in November, 2001, only 4 months after Rice stated Saddam Hussein was not a threat.
"Significantly, the decision is made independent of normal policy-making procedures—a National Intelligence Estimate (NIE) on Iraq was not requested, members of Congress were not consulted, and the concerns of senior military officers and intelligence analysts were ignored."
http://usatoday30.usatoday.com/news/world/2002-09-10-iraq-war_x.htm
According to John D. (Jay) Rockefeller IV, Chairman of the Senate Select Committee on Intelligence,
“Before taking the country to war, this Administration owed it to the American people to give them a 100 percent accurate picture of the threat we faced. Unfortunately, our Committee has concluded that the Administration made significant claims that were not supported by the intelligence,” Rockefeller said. “In making the case for war, the Administration repeatedly presented intelligence as fact when in reality it was unsubstantiated, contradicted, or even non-existent. As a result, the American people were led to believe that the threat from Iraq was much greater than actually existed.”
Bush had to lie, because if he had told the truth--Saddam Hussein is not a threat, but we know he wants to acquire WMD-- the American people would never have allowed the Iraq war.
Who should be held accountable? The evidence is overwhelming that Bush lied. You can only take the premise "he didn't know he was lying" so far before it begins to sound absurd. Considering the consequences of his actions, it's time to stop making excuses for him.
Even before his first term, Bush told his biographer, Mickey Herskowitz:
“One of the keys to being seen as a great leader is to be seen as a commander-in-chief,” Herskowitz remembers Bush saying. “My father had all this political capital built up when he drove the Iraqis out of [Kuwait] and he wasted it. If I have a chance to invade Iraq, if I had that much capital, I’m not going to waste it. I’m going to get everything passed I want to get passed and I’m going to have a successful presidency.”
Hussein was an obstacle for PNAC's objective, to “remain the predominant outside power in the region and preserve U.S. and Western access to the region’s oil.”
It reveals he wanted to invade Iraq even before he was in office. As soon as he took office, he asked his cabinet members to "find a way to attack Iraq," according to Paul O'Neill.
http://www.cbsnews.com/news/bush-sought-way-to-invade-iraq/
Eight months later, 9/11 provided the "Pearl Harbor event" PNAC stated would be needed as a catalyst for war. Cheney, Rumsfeld, Wolfowitz and other PNAC members were (coincidentally) already in place in the Bush administration to carry out the PNAC mission.
Luckily for Bush, 9/11 made war a popular thing. It's why he said he hit the trifecta.
He was wrong about WMD (maybe he should have let Hans Blix finish his work), but he accomplished the PNAC mission. Saddam Hussein is gone, and Bush is now demanding 58 permanent bases in Iraq:
http://www.alternet.org/story/88256/status_of_forces_agreement_will_decide_whether_iraq_is_independent_or_%22a_client_state_of_the_us%22
"The Pearl Harbor of the 21st century took place today." President George W. Bush, in his daily diary, September 11, 2001