Image caption In his memoir Tony Blair argues that Saddam remained a threat because he intended to rebuild his WMD

In his memoirs, former British Prime Minister Tony Blair justified the 2003 invasion of Iraq by saying that he "may have been right" about Iraq and weapons of mass destruction. His argument was that even if Saddam Hussein did not have WMD at the time of the invasion, he intended to rebuild them. Paul Reynolds, world affairs correspondent for the BBC News website, examines this claim.

One of the charges against Tony Blair over the invasion of Iraq is that he exaggerated the evidence for WMD.

Is he now exaggerating the threat that Saddam Hussein would have posed if left in power? Or is there enough evidence to support him?

"I have often reflected as to whether I was wrong. I ask you to reflect as to whether I may have been right... But the true facts do provide the clearest possible basis to assess that he [Saddam] was indeed a threat Tony Blair, A Journey

The line of inquiry leads to Saddam himself but starts in the aftermath of the 2003 invasion.

The Iraq Survey Group, whose job was to find WMD, made an interim report in October 2003 saying it had found none. Its leader David Kay resigned in early 2004 and said of WMD: "I don't think they existed."

Intriguingly, however, in a comment picked up by Tony Blair, Mr Kay told a Senate committee: "I actually think what we learned during the inspection made Iraq a more dangerous place, potentially, than, in fact, we thought it was even before the war."

Hopes and intentions'

His meaning became clear when the ISG, under its subsequent leader Charles Duelfer, issued its final report in September 2004.

It concluded that Saddam hoped in due course to get sanctions lifted and rebuild his WMD.

The ISG summary, quoted by Mr Blair, was this: "Saddam wanted to recreate Iraq's WMD capacity... but probably with a different mix of capabilities... Saddam aspired to develop a nuclear capability... but he intended to focus on ballistic missile and tactical chemical warfare (CW) capability."

This conclusion, Mr Blair said, showed that Saddam had made a "tactical decision to put [his WMD] programme into abeyance, not a strategic decision to abandon it".

Media playback is unsupported on your device Media caption Tony Blair on Iraq: ''I can't regret the decision''

Note that Mr Blair does not follow the distinction the ISG made between the various types of WMD and its belief that Saddam would in future concentrate on chemical weapons and ballistic missiles (because he saw Iran as his main threat and he had beaten off Iran with CW and missiles before).

Note also that Mr Blair uses the word "programme", which implies that Saddam had a plan which was waiting for the go-ahead. Yet the ISG does not say that. It states: "There is an extensive, yet fragmentary and circumstantial, body of evidence suggesting that Saddam pursued a strategy to maintain a capability to return to WMD after sanctions were lifted by preserving assets and expertise."

On the other hand, the ISG does conclude that Saddam's intention was there. It says: "In addition to preserved capability, we have clear evidence of his intent to resume WMD as soon as sanctions were lifted."

Saddam interviews

So where does this belief in Saddam's intention come from? It comes from two sources. The first was interviews with Saddam's associates and scientists. They suggested that this is what their leader would do.

The ISG report quotes Saddam's presidential secretary Abid Hamid Mahmud as saying: "If the sanctions would have been lifted and there is no UN monitoring, then it was possible for Saddam to continue his WMD activities and in my estimation it would have been done in a total secrecy and [with] concealment."

The phrase "if... there is no UN monitoring" is relevant. Mr Blair assumes there would have been none. But if there had been, then Saddam would have had huge problems to overcome and might have been found out. Monitoring might have been the price for lifting sanctions which Mr Blair says were bound to collapse in due course.

The second source was Saddam himself. And here the role of FBI agent George Piro is central. Mr Piro managed to gain Saddam's confidence in captivity.

In a 2008 interview with CBS, Piro said: "[Saddam] wanted to pursue all of WMD. So he wanted to reconstitute his entire WMD programme."

Asked by the interviewer whether this meant chemical, biological, and nuclear weapons, Mr Piro answers definitively that it did.

'What is necessary'

In his book Hide and Seek, Charles Duelfer writes about the moment when Saddam allegedly confessed to his future aims.

"It was the second week in June when Piro came to me, beaming. He related a thoughtful discussion on WMD by Saddam. Saddam clearly stated that it would be his goal to reconstitute his WMD, especially his nuclear, to reassert Iraq's place in the region," Mr Duelfer writes.

However, the report of the Piro-Saddam interview, released under freedom of information laws, is not quite so clear.

The report unfortunately is not a verbatim account. It simply quotes Mr Piro as suggesting to Saddam that, if sanctions had been lifted, and Iran remained a threat, then "it would appear that Iraq would have needed to reconstitute its own weapons programme in response".

The reports goes on: "Hussein replied that Iraq would have done what was necessary and agreed that Iraq's technical and scientific abilities exceeded others in the region."

The claim by the ISG, from Mr Piro through Mr Duelfer, and now to Tony Blair, seems ultimately to rest on this. Saddam does agree that he would do what was necessary. However, he is not specific.

Tony Blair admits in his book that his thesis is not an "indisputable one". He offers this thought: "My point here is not to persuade that we were right to remove [Saddam Hussein], but only to make those who adhere to the conventional wisdom at least pause and reflect."

Paul.Reynolds-INTERNET@bbc.co.uk