Former Treasury Secretary Paul O'Neill (search) contends the United States began laying the groundwork for an invasion of Iraq just days after President Bush took office in January 2001 — more than two years before the start of the U.S.-led war that ousted Saddam Hussein.

"From the very beginning, there was a conviction that Saddam Hussein (search) was a bad person and that he needed to go," O'Neill told CBS's "60 Minutes" in an interview to be aired Sunday night.

The official American government stance on Iraq, dating to the Clinton administration, was that the United States sought to oust Saddam.

But O'Neill, who was fired by Bush in December 2002, said he had qualms about what he asserted was the pre-emptive nature of the war planning.

"For me, the notion of pre-emption, that the U.S. has the unilateral right to do whatever we decide to do, is a really huge leap," according to an excerpt of the interview that CBS released Saturday.

The administration has not found evidence that the Iraqi leader was involved in the Sept. 11 attacks but officials have said they had to consider the possibility that Saddam could have undertaken an even larger scale-strike against the United States.

White House spokesman Scott McClellan (search) would not confirm or deny that the White House began Iraq war planning early in Bush's term. But, he said, Saddam "was a threat to peace and stability before September 11th, and even more of a threat after September 11."

"It appears that the world according to Mr. O'Neill is more about trying to justify his own opinions than looking at the reality of the results we are achieving on behalf of the American people," McClellan said in Texas, where the president is staying at his ranch.

O'Neill's interview was part of his effort to promote a new book about the first half of Bush's term, "The Price of Loyalty," for which O'Neill was a primary source.

The administration began sending signals about a possible confrontation with Iraq even before Sept. 11, 2001.

In July 2001, after an Iraqi surface-to-air missile was fired at an American surveillance plane, Bush's national security adviser put Saddam on notice that the United States intended a more resolute military policy toward Iraq.

"Saddam Hussein is on the radar screen for the administration," Condoleezza Rice said at the time.

Yet Secretary of State Colin Powell (search) said in December 2001, after the terrorist attacks in Washington and New York, that "with respect to what is sometimes characterized as taking out Saddam, I never saw a plan that was going to take him out."

According to the book by former Wall Street Journal reporter Ron Suskind, the Bush administration began examining options for an invasion in the first months after Bush was inaugurated.