Former British Prime Minister Tony Blair said the country's research in the Iraq war, the world must continue the fight against Islamic extremism.
Appearance before the panel in central London for the second time, Blair said it was impossible to handle the threat of extremists.
"The hardest things we face today - and we face ever - is the risk of this new form of terrorism and extremism is based on an ideological perversion of Islam, combined with technology that allows them to kill people on a large scale.
"Although this is a time when many people think that extremism can be managed, I personally do not think that's true. I think you have to challenge and change."
Earlier, dozens of antiwar protesters gathered in front of where the research is carried out, waving banners and chanting: "Justice will prevail: Blair in prison". "Blair lied - thousands of deaths" and
Blair appears before the protests of the Iraq Research
Some, wearing masks of Tony Blair, carried out mock "arrest", the confiscation of the people claiming to be former prime minister on suspicion of war crimes.
The survey Chilcot, headed by a longstanding British civil, has broad powers to investigate British participation in the war in Iraq.
Blair first testified about the investigation in January last year. On Friday, said President John Chilcot former prime minister had been recalled to "clarify" aspects of the events surrounding the invasion of March 2003.
Blair should address the questions about whether he pressures his then-Attorney General Peter Goldsmith, to approve the legality of the war.
As the hearing got under way, he challenged the director Martin Gilbert if he regretted comparing the threat of Saddam Hussein and Nazi Germany in 1930.
Blair admits he should not have involved the circumstances are the same, but insisted he still believed in a "calculated risk" has changed in the wake of 9 / 11 attacks in the United States in 2001.
Blair told his ministers since the start of 2002 that the government had initiated a policy would likely lead Britain into war.
Committee members Roderic Lyne, former diplomat quoted the testimony of the counselor Europe ex-PM, Stephen Wall, who said the government would not have appreciated before January 2003 that military action was likely.
Lyne said it appeared that the government did not discuss Iraq on April 11 and September 23, 2002, when the prospect of war draws ever closer.
He asked Blair if he felt he had the approval of the Cabinet Britain increasingly aggressive policy of Saddam during this period.
"I honestly do not think you could have a minister at the table who would say:" Oh my God, I could not have said that Saddam had complied with UN inspectors or were about to take military action, "said Blair.
"I think I said. Questions Every First Minister I asked him."
"Every day there are stories we have been planning and preparing to launch military action with the United States," he said.
"So the only thing one could have been questioned is whether, where I found myself on this issue or that government policy has been."
Blair was prime minister in view of the war during the invasion and the height of the conflict. He handed over power to Gordon Brown in 2007.
Brown and many other current and former British officials said before the committee.
Blair was predominantly positive during his first appearance, but he admitted that there had been proper planning for what happened after the fall of Saddam Hussein.
The planners did not foresee the role played by the enormous destabilizing Iran and the insurgents, or public service problems in Iraq, "he said.
He insisted that the invasion was legal, based on UNSC Resolution 1441 of Many critics of the invasion "said a new resolution would be needed to authorize the war.
Blair admitted he was "politically" better to have a second resolution. But he said that Hussein was playing with the West and more time would not have solved the problem.
He said Britain and America had slightly different reasons for going to war. Americans, he said, wanted to remove Hussein from power.
The British, on the other hand, was primarily concerned with treatment of the Iraqi dictator "weapons of mass destruction ambitions. If that means regime change, so be it," Blair said.
No WMD, or weapons of mass destruction were found after the invasion.
Iraq inquiry, which began in 2009, is an independent group headed by longtime civil servant John Chilcot. Its objective is to establish what happened before and during the war, and to identify lessons learned from the conflict.
The research focuses on the period from summer 2001 to the present. The military operation began in 2003.