It's not true. Dunlap quotes British Cabinet Minister, Robin Cook, and Australian intelligence officer, Andrew Wilkie. But many other serious analysts said Iraq was not a threat.
As I've pointed out repeatedly, the IAEA (ElBaradei personally) proclaimed before the war, as a result of the most recent inspections, that Iraq had no nuclear program. A threatening nuclear program would be relatively easy to find because of the construction and power needs associated with it. El Baradei was pretty definitive.
The "mushroom cloud" fear was known to be false before the war.
Some private analysts were saying the same thing about the nuclear program long before the war. For example, Joseph Cirincione of the Carnegie Endowment for International Peace declared in August, 2002: "Iraq almost certainly does not have nuclear weapons....There is no evidence that Iraq has a nuclear weapon or will soon have one." Cirincione cited open intelligence from the US that said a bomb would be several years away.
Cirincione believed Iraq had large stocks of chemical and biological weapons, but added:
"Iraq has limited means of delivering any weapon of mass destruction. Iraq has no capability to attack the United States from its own territory and only limited capability to attack neighboring countries by air."
A number of former weapons inspectors, like Scott Ritter, argued that Iraq had no WMD. None. Consider his June 2000 piece in Arms Control Today, "The Case for Iraq's Qualitative Disarmament." Ritter wrote then:
Most of UNSCOM's findings of Iraqi non-compliance concerned either the inability to verify an Iraqi declaration or peripheral matters, such as components and documentation, which by and of themselves do not constitute a weapon or program. By the end of 1998, Iraq had, in fact, been disarmed to a level unprecedented in modern history, but UNSCOM and the Security Council were unable—and in some instances unwilling—to acknowledge this accomplishment.And of course Ritter went around the country in late 2002 and early 2003 saying Iraq was disarmed already.
From academia, Glen Rangwala, Lecturer in Politics at Cambridge University, was very clearly arguing that Iraq was not a significant WMD threat. For example, consider his coauthored piece (with Labour MP Alan Simpson), called "The dishonest case for war on Iraq" dated 17 September 2002. Rangwala wrote this in April 2002, before Iraq was even really on the radar for most people:
This briefing examines the evidence for Iraqi capabilities to launch attacks using WMDs. It finds that there is little evidence to suggest that Iraq retains extensive WMD capacities. Furthermore, US and UK policy towards Iraq since the end of the Gulf War has not been driven by an arms control agenda, suggesting that these governments have not perceived Iraq to be threatening regional or international security through an accumulation of non-conventional weapons.More to come, so expect this to be edited.
Update: A reader reminded me that Colin Powell and Condi Rice were among those saying Iraq had no threatening WMD -- as recently as 2001. I blogged about their statements back in late September.