In the Republican presidential debate in South Carolina on Saturday night, Donald Trump said something about the Bush administration and the Iraq War that is essentially illegal for Republican politicians.

“They lied,” he said. “They said there were weapons of mass destruction, there were none. And they knew there were none.”

Trump has subsequently walked it back a bit, but he shouldn’t have. I’ve followed the issue of Iraq’s WMD programs for 20 years, and won a $1,000 bet in 2003 that if the U.S. invaded, we would find nothing. There’s no question that the Bush administration lied enthusiastically about what it knew about Iraq and WMD.

There is an enormous amount of powerful evidence to prove it:

Former Vice President Dick Cheney kicked off the push for war in August 2002 by claiming: “There is no doubt that Saddam Hussein now has weapons of mass destruction. There is no doubt he is amassing them to use against our friends, against our allies, and against us.” Cheney’s speech had not been vetted by the CIA, and John McLaughlin, the CIA’s deputy director, shortly afterward told Congress that the likelihood of Iraq initiating a WMD attack “would be low.” Another CIA official later recalled that the agency’s reaction to Cheney’s speech was, “Where is he getting this stuff from?”

The Bush administration said that aluminum tubes Iraq had tried to import were “only really suited for nuclear weapons programs” — even as Bush himself was being told the State Department and Energy Department believed (correctly, of course) they were intended to be used as conventional rockets.

Bush declared in his 2003 State of the Union address that “Saddam Hussein recently sought significant quantities of uranium from Africa,” even though his administration had been repeatedly warned this was dubious (and it turned out to originate with crudely forged documents).

Colin Powell doctored intercepted Iraqi communications for his U.N. presentation to make them appear more alarming.

… and much more.

There’s also one specific story proving they lied that I think hasn’t received enough attention: the curious case of Saddam Hussein’s son-in-law Hussein Kamel.

Kamel was a powerful figure in the Hussein regime, perhaps second only to Saddam himself, and had been in charge of Iraq’s completely real WMD programs in the 1980s during the Iran-Iraq War. After Iraq was pushed back out of Kuwait by a U.S.-led coalition in 1991, the U.N. Security Council decreed that its harsh sanctions on Iraq would remain until Iraq was disarmed of all WMD programs.

By 1995, Kamel was disillusioned with Hussein’s rule and defected to Jordan. There he told the United Nations, the International Atomic Energy Agency, the CIA, and British intelligence an interesting story: Iraq was in fact disarmed, with no remaining chemical, biological, or nuclear weapons programs of any kind. All that remained hidden, he said, was documentation from the 1980s programs, which the U.N. shortly seized from Kamel’s farm back in Iraq.

While the details of Kamel’s debriefing were not public at the time, he went on CNN to openly declare that “Iraq does not possess any weapons of mass destruction.”

Kamel quickly realized that the world outside Iraq was not as hospitable as he’d expected, and, in particular, that the U.S. would not send troops to Baghdad in order to oust his father-in-law and put him in charge. In early 1996 he returned to Iraq, where he was promptly assassinated.

As the U.S. evaluated the Bush administration case for war six years later in the fall of 2002, Kamel’s statements should have been critical information. Certainly Bush officials felt they were: A post-war commission investigating the WMD intelligence debacle mentioned a “Senior Executive Memorandum” of January 12, 2002, “discussing the value of Kamil’s [sic] information.” Senior Executive Memoranda are generally produced by the CIA at the request of high-level officials in the executive branch.

This is where the lies about Kamel began. If the Bush administration wanted to grapple honestly with Kamel’s story, it would have had to make the case that either Kamel had been lying in 1995 or Iraq had restarted its WMD programs after his defection, or both.

Instead, the administration turned reality completely on its head. In the same August 2002 speech mentioned above, Cheney claimed this:

We now know that Saddam has resumed his efforts to acquire nuclear weapons. Among other sources, we’ve gotten this from the firsthand testimony of defectors — including Saddam’s own son-in-law [Hussein Kamel].

This lie should have been easily caught by the U.S. media, given Kamel’s 1995 CNN interview. Moreover, there were public documents sitting on the IAEA website stating the Kamel had told the agency “all nuclear weapons related activities had effectively ceased” in 1991.

Cheney’s lie didn’t even make sense: Inspectors were still in Iraq when Kamel defected, so if he’d told them Iraq had a nuclear weapons program, the IAEA would have dismantled it.

Yet none of that made any difference. With no one pointing out Cheney’s blatant falsehood, the rest of the Bush administration eagerly made use of Kamel.

Several weeks later, in September 2002, Donald Rumsfeld told Congress the U.N. inspections would be useless without informants like Kamel. However, he didn’t mention that Kamel had informed us that Iraq had nothing:

Unless we have people inside the Iraqi program who are willing to tell us what they have and where they have it — as we did in 1995 with the defection of Saddam’s son-in-law, Hussein Kamel — it is easy for the Iraqi regime to hide its capabilities from us.

Shortly afterward, Bush himself mentioned Kamel, as did Colin Powell in his address to the U.N. Security Council.

This so infuriated someone with access to the detailed notes from one of Kamel’s original debriefings that he or she leaked them to Newsweek, which finally published a brief story about Kamel on March 3, 2003, just a few weeks before the war began. Newsweek did not mention Cheney’s lie about Kamel, but did explain that “the defector’s tale raises questions about whether the WMD stockpiles attributed to Iraq still exist.”

When subsequently questioned by Reuters for a follow-up story, the CIA and MI6 were clearly terrified and went ballistic. The British hilariously claimed that “We’ve checked back and he didn’t say this. He said just the opposite, that the WMD program was alive and kicking.” According to the CIA’s then-spokesperson Bill Harlow, the Newsweek story was “incorrect, bogus, wrong, untrue.” (Harlow, who now makes a living defending the CIA’s torture program, recently told me that “I have no intention to engage in an exchange about that single answer to one of the thousands of questions I handled in that job more than a decade ago.”)

The CIA’s fear was understandable. At just about the same time, Alan Foley, the head of the CIA division in charge of analyzing Iraq’s purported WMD programs, was — according to retired CIA analyst Mel Goodman — privately saying that Iraq possessed “not much, if anything” related to WMD.

The rest of the story is well-known: The U.S. and allies invaded Iraq on March 19, 2003, and Iraq had become a perpetual vortex of violence that may pull in the entire Mideast. We now know not just what Kamel had said in 1995, but that he’d been telling the truth.

Thus even if you disregard the mountains of evidence that the Bush administration shaded the truth, omitted pertinent facts, and straight-out lied in other areas, the story of Hussein Kamel tells you everything you need to know. Indeed, the Bush administration’s campaign of deceit was so successful at so little real cost that it continued with even more brazen post-invasion lies. For instance, Bush went on to claim that Saddam Hussein “absolutely” had WMD programs and repeatedly said that Iraq “wouldn’t let [U.N. inspectors] in.”

So hopefully Trump won’t buckle to the pressure from the Republican establishment to proclaim that the Bush administration’s WMD claims were all just an honest mistake. They weren’t, and Trump was absolutely right.