Tony Blair said he understood why some families of service personnel killed in Iraq "can never forgive me" as he continued to defend his actions following the damning report by Sir John Chilcot into the war.
The former prime minister was found to have sent in forces in 2003 when there was no "imminent threat" from Saddam Hussein and on the basis of "flawed" intelligence about the Iraqi dictator's weapons of mass destruction programme.
Mr Blair insisted the sacrifices made by British troops had not been in vain and maintained that it was right to remove Saddam from power.
He was challenged about the families of service personnel killed in the conflict, some of whom want him to face trial for war crimes.
Asked if he had considered whether that could happen, Mr Blair said: "No, but I do understand why they can't agree with me and will never forgive me for this decision.
"But I also think you put prime ministers in these positions to take decisions and to take them in what they believe to be the best interests of the country.
"That's not to say those decisions are right, but you always want your prime ministers to be sitting in that seat of decision-making and doing what they think is right. Because that's what you elect them to do."
He added: "I never expected to end up being prime minister in a time of war. I never expected to go into conflict. I came in in 1997 full of plans for the health service and education and all the rest of it."
The former premier has made a series of media appearances since the Chilcot Report's publication on Wednesday in an attempt to explain the decision which has come to define his time in office.
"They did not make that contribution or sacrifice in vain," he told Forces TV. "In my view, in my judgment, at the time and now, the world was and is better off without Saddam Hussein in power."
He said the military was fully prepared for the campaign to remove Saddam, but that the terrorist insurgency that followed was "tough".
Sir John found that "despite explicit warnings, the consequences of the invasion were underestimated" and planning for Iraq after Saddam's removal was "wholly inadequate".
Mr Blair said: "You can do all the planning but in the end it's the fighting that's going to be tough. Because, however much you plan, if you have people who are prepared to drive cars laden with explosives into markets where there are civilians and blow up the first 100 people they see, you are going to have a tough fight."