As controversy deepens over why none of Saddam's weapons of mass destruction have yet been found, the US National Security Adviser, Condoleezza Rice, was wheeled out this week - looking decidedly uncomfortable - to defend the decision to go to war.

CONDOLEEZZA RICE, US NATIONAL SECURITY ADVISER: Well the President believes that he had very good intelligence going into the war. He stands behind what the Director of Central Intelligence told him going into the war. Obviously this was the accumulation of evidence about Saddam Hussein's weapons of mass destruction over a 12-year period. Information that was relied on by three administrations, several different intelligence services and indeed, the United Nations itself.

Now, speculation is growing that Iraq was effectively disarmed - or even disarmed itself - after the first Gulf War. Tonight we hear from three weapons inspectors who worked on the ground in Iraq to locate and destroy Saddam's arsenal.

SCOTT RITTER, FORMER UNSCOM INSPECTOR: Is it possible Iraq destroyed their weapons in '91? Absolutely.

JOHN GEE, FORMER UNSCOM COMMISSIONER: Then why did they try and hide it and why didn't they come clean earlier and save themselves a lot of trouble?

NEIL JAMES, FORMER UNSCOM INSPECTOR: The other school of thought was, that we had been set up to fail.

The inspectors of the UN Special Commission, or UNSCOM, went into Iraq in May 1991 with the backing of both resolution 687 - unprecedented in its toughness on a member state - and a Security Council seemingly united like never before. Inspections - like this one at the vast al-Muthanna chemical plant - were meant to be a cooperative endeavour. UNSCOM soon found that cooperation lacking.

JOHN GEE: I recall that the first declaration of Iraqi chemical weapon artillery shells was just 105 of them. Now that was clearly woefully inadequate.

False declarations fuelled an atmosphere of mutual distrust as UNSCOM set about destroying what few weapons were declared. Australian diplomat John Gee was one of 21 commissioners appointed to get UNSCOM up and running.

JOHN GEE: I think increasingly, as the months went by in 1991, we realised that was going to take a long time. So I think in essence it was always going to be a race against time. Because it was inevitable, too, that at some stage the political support for UNSCOM, that had been so strong at its outset, was going to fade.

UNSCOM INSPECTORS: We're ready to go and there are two cars blocking our way. We are inspectors, we want out.

The sort of early obstruction UNSCOM encountered was beamed around the world in September 1991.

UNSCOM INSPECTORS: You're keeping at team of 45 inspectors waiting...

Inspectors, including the man leading the current weapons hunt, David Kay, were involved in a 4-day stand-off in a government carpark. Kay - now employed by the CIA - is currently in Washington, preparing an interim report into his latest work - involving the 1,200 investigators of the American-backed Iraq survey group. Some of that report has already been leaked, revealing that no weapons have been found. That news forced John Howard last week to defend HIS decision to go to war - and his response was remarkably similar to that of the US Administration.

JOHN HOWARD, AUSTRALIAN PRIME MINISTER: I did say the principal reason was the possession of weapons. And my belief in relation to that was based on the intelligence we had at the time - it was very strong.

In its early days, UNSCOM realised that apart from poking around leaky barrels or destroying declared weapons, intelligence would be the key to its operation. It had been relying on information from nations like the US and Britain, but soon set up its own "information assessment unit". Over time, the balance shifted between the inspectors and the intelligence agencies.

JOHN GEE: They didn't have on-the-ground access - the on-the-ground access that we had. So the situation changed to the point where in fact after a couple of years, it was UNSCOM that became the repository of knowledge on Iraq.

But being a "repository of knowledge" increased the tension between UNSCOM and the rogue regime.

JOHN GEE: It was very easy for the Iraqis to just misrepresent UNSCOM and say that our intentions, they were solely... were principally nefarious and for espionage, rather than simply for getting rid of weapons of mass destruction.

Neil James is a former intelligence officer in the Australian army who served with UNSCOM. This is the first time he's spoken in detail about his experiences in Iraq during this critical period. He has no doubt that Iraq was involved in plenty of espionage of its own.

NEIL JAMES: Some of our more sensitive briefing sessions when you were taking the team out were literally silent briefs - I mean you sat round a table and gave them something to read, and no-one asked questions. And even some of the cars were bugged, and so if you were travelling to a site you had to be a little bit careful what was said in some of the vehicles.

But already, the Iraqis were making a key admission. They led inspectors to sites where - they claimed - they'd secretly destroyed their illegal chemical and ballistic-missile stocks in July of 1991. But with no documentation of exactly what was destroyed, and how much there was to begin with, this unilateral destruction became yet another mystery for UNSCOM to solve.

SCOTT RITTER: They destroyed material without adequate documentation. And because Iraqi had a history of lying to the inspectors the inspectors were want to accept at face value the Iraqi claims. And that's what it hinges on - it's an accounting issue.

Even so, as UNSCOM's own footage shows, progress was being made. Helicopters equipped with ground-penetrating radar made sweeps of the Iraqi desert. Caches of chemical bombs, when found, were blown up. Long-range missiles - Scuds and al-Husseins - were crushed. John Gee says by this stage the inspectors had made major inroads into Iraq's disarmament.

JOHN GEE: Paradoxically in a sense UNSCOM became a victim of its own success, because, by 1994, a great deal had been achieved in relation to the destruction of ballistic missiles, chemical weapons and the supporting capabilities. A number of Iraqi nuclear facilities had been destroyed at that stage. And a number of countries were starting to ask the question - how much longer is this sort of process going to go on, and is it really necessary?

What remained completely unaccounted for was what Iraq had produced in facilities like this. UNSCOM was convinced that Iraq had a hidden biological warfare program - something that Iraq continually denied. In July 1995, the denials stopped. UNSCOM's Executive Chairman, Rolf Ekeus, was summoned to Baghdad to be told that Iraq had indeed possessed an offensive biological weapons program.

Just weeks later the head of that program - Saddam's son-in-law, Hussein Kamal - made a dash for the Jordanian border. Before he was lured back to Iraq and execution, the high-ranking defector told Ekeus that all of Iraq's illegal weapons had been destroyed and the programs shut down. In Iraq, it was confession time - Baghdad handed over a million pages of documentation - including more information about its Biological Warfare, or BW program.

JOHN GEE: For the first time, in documented form, the scope of the Iraqi BW program became clear. Now whether that's its full scope, frankly I'm not sure that I'm in a position to say. But certainly that was a very significant step forward.

Armed with this new information, the inspectors were able to hunt down what was left of Iraq's hidden, decommissioned stocks - this biological bomb, for instance, dredged out of the Tigris canal. UNSCOM later estimated that the biological breakthrough enabled it to complete 90% to 95% of Iraq's disarmament - a statistic that's been ignored in the latest controversy. Scott Ritter was one of UNSCOM's most controversial inspectors - constantly clashing with the Iraqi regime and calling for a tougher line from the UN. Now a strident critic of US policy on Iraq, he goes even further.

SCOTT RITTER: Well, I think the fact is we knew everything, we knew everything there was to know about the Iraqi biological weapons program, everything that we needed to know and yet we were dismissive of it. And you have to ask yourself why?

JOHN GEE: The question I suppose that then arises is - well if they had nothing left - and that's now looking to be a distinct possibility - nothing left or at least very little left - then why did they try and hide it and why didn't they come clean earlier and save themselves a lot of trouble?

SCOTT RITTER: The CIA was in Iraq to get Saddam. And when you consider that, now suddenly it makes sense that the Iraqis obstruct and obfuscate when issues touch on, what they feel is their legitimate national security.

John Gee suggests that Saddam's hubris may have prevented him from admitting he'd been disarmed...

JOHN GEE: For him then to turn round later on and say that he didn't have them would call into question his own role and his claim to be the champion of the Arab cause as it were - whether it's against the West or against Israel.

..or that his underlings were too frightened to tell him that the weapons were gone.

JOHN GEE: You were liable not to have your job much longer you might not even have your life much longer. It was that sort of regime.

After the honeymoon period surrounding Hussein Kamal's defection, relations between Iraq and the inspectors grew worse than ever. Iraq maintained it had now come clean and that crippling sanctions imposed by the UN Security Council should be lifted.

TARIQ AZIZ, FORMER DEPUTY PRIME MINISTER OF IRAQ, 1997: We've told UNSCOM since the end of 1991 that the weapons were destroyed. They did not take that. Well, since 1992 till now - five years after that declaration - they have been searching Iraq round the clock, round the clock, every day, every week, every month. They haven't seen, they haven't found any trace of weaponry!

But as long as Saddam Hussein remained in power, the United States was making it clear that sanctions would remain in force.

JOHN GEE: I think once they realised they had made a mistake in 1991 - in not getting rid of Saddam then, at least as they would see it - their ultimate objective was always regime change. That I think was one constant element in American policy. And this of course - and I'm sure the Iraqis saw it in those terms as well.

REPORTER: And with America wanting regime change there's also the theory that America was quite happy to spin out the process and keep WMD as a potential card to play against the regime.

JOHN GEE: I wouldn't know about that.

SCOTT RITTER: What was needed to sustain the necessity of removing Saddam Hussein was the perception that Saddam Hussein posed a threat to the US.

Scott Ritter's outspoken attacks on the US Government over its Iraq policy have seen him branded a traitor by senior administration officials. But the former Marine believes both he and UNSCOM were betrayed by the CIA.

SCOTT RITTER: The United States never provided the intelligence they promised us.

In 1997, Ritter led a series of inspections designed to flush out hidden missiles. The spectacular failure of that mission convinced him that the CIA was gunning for UNSCOM. Neil James also contemplated the startling possibility that the mission was set up to fail.

NEIL JAMES: The inspection was...came a complete cropper. We weren't prepared to dismiss the fact that it had been deliberately sabotaged.

James was a member of Ritter's team.

NEIL JAMES: Some of the planning materials we'd been given were actually inaccurate, like the north arrow was 180 degrees out, for example. Some of the grid references we'd been given were wrong. I can remember being very pissed off at the time that we'd put all this effort in and I had, on the ground, discovered quite amateurish mistakes.

Scott Ritter says it wasn't just the maps that were wrong - carefully timed overflights by U2 spy-planes, equipped with motion sensors, mysteriously didn't happen.

SCOTT RITTER: The United States didn't fly these sensors or fly during the time period we wanted. They didn't fly the routes we wanted, they flew everywhere but where we wanted.

More suspicious for Neil James was that communications systems supplied by the US simply didn't work.

NEIL JAMES: Yeah, they continuously failed - I mean it was... There are two schools of thought here - one was that it was just one of those things and the other school of thought was that we were set up to fail.

James was called to Washington, to be debriefed. During one session he witnessed an unseemly brawl as one branch of the CIA accused the other of either incompetence or deliberately sabotaging the mission.

NEIL JAMES: Well they were a bit careful what they said because there were outsiders in the room, you know, both UNSCOM outsiders and non-CIA outsiders. But, essentially, the Directorate of Intelligence were accusing the Directorate of Operations of either bungling or deliberately messing up the communications. And the boys from the Directorate of Operations were not happy to be accused of this.

Scott Ritter says the motives were clear.

SCOTT RITTER: In order to sustain your allegation that Iraq has weapons, you have to destroy the credibility and confidence that the international community has in the inspection process. And that was the purpose of this series of inspections carried out in the spring and summer of 1997.

At the end of 1998, the then-head of UNSCOM, Richard Butler, pulled the team out, citing non-cooperation from Iraq. By then, the inspectors were deep in controversy over allegations that material they were collecting was going straight back to the CIA, in contravention of UNSCOM guidelines.

JOHN GEE: Certainly, allegations that UNSCOM officials were carrying out espionage activities certainly didn't help.

On Friday, the newly apolitical Richard Butler will be sworn in as Tasmania's new Governor - and he declined to be interviewed for this program. But in an earlier Dateline interview, this excerpt of which was never broadcast, he made an extraordinary admission that seemed to support the worst fears of the other inspectors. Under his stewardship, UNSCOM was infiltrated, not only by Iraq, but also by Western intelligence agencies.

RICHARD BUTLER, FORMER CHIEF UN WEAPONS INSPECTOR: We weren't spies. We were spied on, comprehensively, by the Iraqis and by some people within my own organisation - some of our so-called 'friends' supplied us staff who were then reporting to their home governments.

But he remains convinced that Iraq did retain weapons of mass destruction throughout the inspections process.

RICHARD BUTLER: They had them, there's no question. Even the most sceptical of members of the Security Council - and I would name in particular the Russians and the French - they know that, they know that when Saddam threw me and my team out in 1998, there remained residual weapons.

If Saddam did indeed have weapons up until 1998 there's still no sign of them whatsoever. And the new spin from the Bush Administration is now not about actually having weapons, but acquiring them, or programs for building them.

CONDOLEEZZA RICE: There was an enrichment of the intelligence from 1998 over the period leading up to the war, and nothing pointed to a reversal of Saddam Hussein's very active efforts to acquire weapons of mass destruction and to have very good programs of weapons of mass destruction. It was very clear that this had continued and that it was a gathering danger.

As evidence mounts that the weapons were gone, the world's most powerful leaders can only say "Trust us, something will turn up."