Chilcot report: The aftermath

In a scathing piece of understatement, the report says its does "not agree hindsight is required".

It attacks what it says was a calamitous decision to stand down the Iraqi army and dissolve the Iraqi state and denounces the initial planning and preparations for the aftermath of the invasion as "wholly inadequate".

It also reveals that ministers were given explicit warnings about what would eventually happen, while some of the problems were foreseen by Tony Blair in a note to George Bush before the invasion.

"I will be with you whatever,” he wrote to the US President. “But this is the moment to assess bluntly the difficulties. The planning on this and the strategy are the toughest yet. This is not Kosovo. This is not Afghanistan. It is not even the Gulf War."

One major issue was a misunderstanding of how Iraq worked.

The military did not comprehend the political, cultural and ethnic tensions in the country.

And so they ploughed ahead with the "de Ba’athification" of Iraq's ruling elite.

The Ba’ath party was felt to be fatally undermined by its close links with Saddam.

But what the invaders failed to understand was the sheer numbers of ordinary Iraqis involved in the party, many of whom had a deep antipathy towards the dictator who had ruled their country for more than a generation.

Britain’s "de Ba’athification" of Iraq had a "a significant and lasting negative impact".

In the end the British excluded too many skilled, experienced people from public life in the wake of the war.

Some unceremoniously made unemployed and effectively barred from the job market were left with little reason to buy into any future vision of their state.

"Limiting de Ba’athification to the top three tiers of the party, rather than extending it to the fourth, would have had the potential to be far less damaging to Iraq’s post invasion recovery and political stability," according to the report.

And yet the British had been warned about the risks and dangers involved, it found.

"The UK chose not to act on its well founded misgivings about handing over the implementation of de Ba’athification policy to the Governing Council."

The report also rejected Mr Blair's claim that the threat of armed insurgents causing instability after the invasion could not have been known in advance.

The former Labour leader told the inquiry it had not been possible to foresee Iraq's collapse into sectarian fighting and violence, much of it whipped up by al Qaida and neighbouring Iran.

Sir John said: "We do not agree that hindsight is required. The risks of internal strife in Iraq, active Iranian pursuit of its interests, regional instability and al Qaida activity in Iraq were each explicitly identified before the invasion."

Sir John also said that information available to ministers had been "clear”.

And the report suggested that those who wish to lay the blame for the rise of Islamic State (IS) at the door of the Iraq War may have a case.

Parts of the country now lie in the hands of the IS.

Mr Blair was warned explicitly by advisers in early 2003 that invading Iraq would “heighten” the threat from Al Qaeda and other Islamist extremists.

He was told that extremists would “continue to represent by far the greatest terrorist threat to Western interests” and try to seize Saddam's arsenal of weapons.

By 2007 top secret reports show the security services were concerned about the increasing power in Iraq of jihadi groups.

One dated March 2007 reads: “There is no shortage of suicide bombers. AQ-I [al-Qaida in Iraq] is seeking high-profile attacks. We judge AQ-I will try to expand its sectarian campaign wherever it can: suicide bombings in Kirkuk have risen sharply since October when AQ-I declared the establishment of the notional ‘Islamic State of Iraq’ (including Kirkuk).”

Dame Eliza Manningham-Buller, the former head of MI5 told the inquiry: “By 2003/4 we were receiving an increasing number of leads to terrorist activity from within the UK … our involvement in Iraq radicalised, for want of a better word … a few among a generation … [who] saw our involvement in Iraq, on top of our involvement in Afghanistan, as being an attack on Islam.”

The report concludes: "The government, which lacked both clear ministerial oversight of post-conflict strategy, planning and preparation, and effective co-ordination between government departments, failed to analyse or manage those risks adequately."

The report also found that UK ministers and officials were working on the mistaken assumption that there would be "a well-executed US-led and UN-authorised” plan of action after the invasion.

But the inquiry found officials should have been aware of a "significant risk" that this would not be the case.

The UK tried to persuade US president George Bush that the United Nations should lead the administration in Iraq in the immediate aftermath of Saddam's removal.

But the Americans rejected this idea.

As an alternative ministers got the White House to agree to UN authorisation of a coalition-led interim government.

"Before the invasion of Iraq, ministers, senior officials and the UK military recognised that post-conflict and military operation were likely to be the strategically decisive phase of the coalition's engagement in Iraq.

"UK planning and preparation for the post-conflict phase of operations, which rested on the assumption that the UK would be able quickly to reduce its military presence in Iraq and deploy only a minimal number of civilians, were wholly inadequate.

"The information available to the Government before the invasion provided a clear indication of the potential scale of the post-conflict task and the significant risk associated with the UK's planned approach."

Sir JOhn said that Mr Blair: "did not establish clear ministerial oversight of UK planning and preparation.

"He did not ensure there was a flexible, realistic and fully resourced plan that integrated UK military and civilian contributions and addressed the known risks.

"The failure in the planning and preparations continued to have an effect after the invasion."