Straw says Iraq 'most difficult decision' in his life
Jack Straw: 45 minutes claim has "haunted us ever since"
Jack Straw has said backing the invasion of Iraq was the "most difficult decision" he has ever taken.
The former foreign secretary said he acted "on the basis of the best evidence available at the time" about the threat posed by Iraq.
But he told the Iraq Inquiry that the 45-minute claim about Saddam Hussein's weapons had "haunted us ever since".
Mr Straw, the most senior person to appear, said if he had opposed the war the UK would not have taken part.
In a three-hour session, Mr Straw said he had "very reluctantly" backed the war after the failure of diplomatic efforts and clear evidence Saddam was not complying with international pressure on him to disarm.
He spoke of the "profoundly difficult moral and political dilemma" he faced as he regarded the US policy of regime change as the objective of military action in Iraq as "improper and unlawful".
However, the justice secretary insisted Saddam posed a "serious threat" that must be addressed.
Mr Straw is the first serving cabinet minister to give evidence to the inquiry - which is examining the background to UK involvement in the March 2003 war and its aftermath.
AT THE INQUIRY
Peter Biles, BBC World Affairs correspondent:
Without doubt, this was one of the most important sessions of evidence heard at the Iraq Inquiry so far.
Sir John Chilcot's committee was especially keen to establish whether there had been differences of opinion between Jack Straw and Tony Blair over Iraq.
Mr Straw said he had always offered the former prime minister his "best judgment and loyalty", but in the same breath he made it clear there were always strong views and debate within government.
The sense which Jack Straw gave, was of a foreign secretary drawn into supporting the Iraq war, but with deep reluctance.
He did not give up hope that diplomacy might prevail until, on the eve of war in March 2003, he saw President Jacques Chirac make an announcement on TV that France would veto a second UN resolution.
Mr Straw said this "great Chiracian pronouncement" had been designed to be "totally disruptive".
Jack Straw's 25-page written statement, issued as he arrived at the inquiry, was more strongly worded than any of today's testimony, describing his "deep regret" at "the grave loss of life" in Iraq.
In a written statement published as he began to be questioned, Mr Straw said he was "fully aware" that, as foreign secretary, his support for military action would be "critical" if the UK was to commit troops.
"If I had refused that, the UK's participation in the military action would not have been possible," he said.
"There would almost certainly have been no majority in cabinet or in the Commons."
Mr Straw said he never considered resigning over the issue although he would not have been able to support British involvement without the "explicit" consent of Parliament.
Mr Straw pointed out that US had backed the principle of regime change in Iraq since 1998 but this was never British policy.
"It was not our policy in 2002 nor in 2003," he said. "There would have been no legal basis for it ever being our policy."
He said he would never have "been a party" to such a policy: "I regarded it [the policy of regime change] as improper and self-evidently unlawful."
During the spring of 2002, when Mr Blair had a crucial meeting with President George W Bush in Texas, Mr Straw said there was a "debate" taking place in government about the best way to deal with Iraq.
Before that meeting Mr Straw wrote to Mr Blair - in a letter subsequently leaked - that "regime change per se is no justification for military action: it could form part of the method of any strategy, but not a goal".
Asked whether No 10 had "pre-empted" the Foreign Office over Iraq policy, Mr Straw said Mr Blair was "aware" that regime change could not be a basis for acting against Iraq nor could it be "disguised" as such.
However, asked to what extent his views differed from the prime minister, Mr Straw said the panel must ask Mr Blair that.
Mr Straw was asked about private correspondence between Mr Blair and President Bush at the time in which Mr Blair indicated the UK "would be" with the US if diplomatic efforts failed and it came to military action.
Jack Straw:"A foreign policy of regime change I regarded as improper"
"Would I have written the memorandum in the same way? Probably not. I am a different person."
But he said the letters were part of a trust-building exercise between the two leaders which ultimately led to the US agreeing to seek UN approval for further action on disarming Iraq.
Mr Straw said the case for military action was "in no sense based on intelligence alone" but took account of other factors such as Saddam's history of using weapons of mass destruction and his "open defiance" of the UN.
But he admitted the claim in the September 2002 intelligence dossier on Iraq that chemical weapons could be used within 45 minutes of an order being given should have been "much more precise".
"That was an error, an error that has haunted us ever since."
Mr Straw said the UK insisted on a series of conditions for its backing for military action, including approval by the UN, that it must be a last resort and must be lawful.
January-February: Jack Straw, Tony Blair and other senior Labour figures to appear before the panel
February: Inquiry to adjourn ahead of the general election campaign
June-July: Inquiry to resume and hear from Gordon Brown among others
Report set to be published in late 2010 or early 2011
He helped negotiate a UN resolution in November 2002 giving Saddam Hussein a "final opportunity" to meet its disarmament obligations but failed to get a second resolution which, critics say, was needed to explicitly authorise military action.
Nevertheless, Mr Straw said Saddam Hussein had clearly failed to comply with the initial resolution in terms of co-operating with inspectors and providing full disclosure of his weapons capability.
He said Saddam started to comply in the wake of the November resolution but that soon changed and a 7 March report by weapons inspectors highlighted growing concerns.
"To the degree they were complying, they were only complying because a very large military force was at their gates. That's the truth."
Liberal Democrat foreign affairs spokesman Ed Davey said: "Jack Straw's insistence that he used his 'judgment' rather than solid proof of the existence of weapons of mass destruction is a weak defence of his role in this disastrous war.
"It is clear he is desperate to distance himself from Tony Blair's unrepentant belief he would have got rid of Saddam whatever it took."
Tony Blair is due to give evidence on 29 January, soon after which the inquiry will adjourn ahead of the general election campaign.
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