London (CNN)Former British Prime Minister Tony Blair says the world is living with the "pain" of the wars in Iraq and Afghanistan that occurred during his time in office.
Tony Blair: We live with the 'pain' of Iraq, Afghanistan wars
But we must not become "incapacitated by it," he told CNN's Christiane Amanpour.
Amanpour challenged him on the point.
"Do you feel a sense of responsibility," she asked, "that people still point to what you did and what Bush did, and they say, 'Never again. We are not going there.' So lives are being lost because of what you all did."
"I feel a huge amount of challenge," he said, "and pain about the situation that we've experienced since 9/11 -- which is still the worst terrorist atrocity the world has seen."
That attack, he said, came "before any foreign intervention."
ISIS, with its cascading attacks around the world, grew, at least in part, out of the al Qaeda in Iraq resistance that fought the Western intervention in Iraq.
"When you've got Boko Haram in Nigeria and across parts of sub-Saharan Africa, you've got other groups, you've got Al-Shabaab, you've got groups in central Asia, groups in the Far East -- you know, at some point we've got to realize we didn't cause this problem, we got caught up in it," Blair said.
The attacks by ISIS in Paris and on a Russian airplane over the Sinai Peninsula have led to an increasingly heated debate over how to take on the terrorist group.
Many say countries opposing ISIS have no choice but some form of military intervention, but there is a strong sense of reluctance among others because of the consequences of the wars in Iraq and Afghanistan.
"Really, what I've been trying to say to people is that when you learn the experience -- not just of Afghanistan and Iraq, but of Libya and Syria -- certain lessons are very clear. Intervention is tough; partial intervention is tough; nonintervention is tough, right?" Blair said.
"So the answer is it's going to be a long, hard fight. But you have to deal with the broader ideology that gives rise to this fanaticism, not just the fanaticism."