Seven years after it began, the official inquiry into the UK's role in the 2003 Iraq war is finally set to be published on Wednesday.

The inquiry, led by Sir John Chilcot, was launched in 2009 as British troops withdrew from Iraq. It was tasked with investigating the lead-in to the US-led war in 2003.

Britain's involvement has remained a divisive issue. Former Prime Minister, Tony Blair -- who has been accused of misleading the country into the war -- is expected to face severe criticism.

The 2.6-million word Chilcot Report heard from about 150 witnesses and looked at more than 150,000 government documents.

"There was a sense in which after Bosnia and Kosovo and Sierra Leone and the rapid overthrow of the Taliban, we and the Americans thought intervention was relatively easy," said Malcom Chalmers, Dep. Dir. Gen. of Royal Institute of Defense & Security Studies. 

"It wasn't without its costs but it was something we could achieve relatively quickly and provide the very positive humanitarian outcome for the people involved on the ground, whether it is in Kosovo or Sierra Leone or wherever. And that was the expectation in Iraq and, of course, entirely the opposite was the case."