Tony Blair’s acceptance that the Iraq war facilitated rise of Isis is a first step to acknowledging the conflict was a disaster

Tony Blair’s admission that there are “elements of truth” in the idea the invasion of Iraq in 2003 assisted the rise of Isis is a step forward, and not just for the former Prime Minister. For it represents progress in coming to some sort of understanding about that ill-starred adventure and its longer-term consequences.

Welcome as they are, though, his comments and all previous memoirs, histories, inquiries, apologies and semi-apologies are no substitute for a thorough investigation into the decision to go to war that had such grievous consequences. The cruel, murderous, disastrous results of the illegal Anglo-American invasion of Iraq are still being felt across the Middle East and, indeed, the world.

A great arc of permanent violence has opened up from Nigeria to Somalia to Afghanistan and, through terrorism, far beyond. It would be wrong to label this a third world war, but in its global reach and irreconcilable enemies, its destruction of nations and cities, and its generation of mass movements of peoples, it certainly qualifies as a war. That we can trace the plight of Syrian and Iraqi refugees back to those conversations between Mr Blair and President Bush at Camp David is now acknowledged by at least one of those men.

We should long ago have had the benefit of a comprehensive uncovering of the truth in the Chilcot report. We are told a timetable for publication will be set out next week, and there always has to be some question about whether Mr Blair’s latest revelations are related to that. Mr Blair would not be the skilful politician we know him to be if he didn’t want to get his spin on the matter aired first.

Perhaps that is unduly conspiratorial – but Mr Blair did take the opportunity to repeat his old line about not apologising for the removal of Saddam Hussein. The risposte to that must be that toppling a dictator could not, by itself, justify an illegal war based on overstated intelligence about weapons of mass destruction. Twelve years on it is clear that the late Robin Cook was right: had Saddam continued to be “caged” by no-fly zones and sanctions, we might not have seen the loss of millions of lives.

Mr Blair, however, may be right that the Arab Spring might have brought upheaval to the region anyway – but when Iraq was so destabilised it is impossible for him to deny that the Spring might have turned into a brighter political season than it eventually did had the 2003 invasion not occurred. The rise of Isis was not an inevitability; it was the necessary consequence of an ill-conceived and unwinnable “war on terror”. This also allowed the Taliban to make a comeback in Afghanistan, a further calamity.

This modern history matters because it is part of achieving a sort of justice for those civilians and service people who lost their lives and whose loved ones or were injured in these conflicts. We need to understand, too, how we got into this mess so we might better get the world out of it.

Even so, whatever Mr Blair says now will not, in the short run, save a single refugee child from drowning in the Mediterranean or freezing in a mountain camp in Lebanon or the Balkans. It will not prevent a single woman being raped by militants from Isis, al-Shabaab or Boko Haram, nor the attempted genocide of minorities and destruction of human rights and cultural heritage. We shouldn’t let the events of 2003 distract us from action now.

The Chilcot report should help us understand where we go from here; but events are moving in utterly unpredictable ways. What we in the West need is the ideas, the policies and the materials – financial, intelligence, political, diplomatic, religious, military – and, above all, the willpower to decide what to do next and see it through. In 2003, at least to Mr Bush and Mr Blair, the problems seemed clear cut, the course of action compelling and the armed forces to effect it readily available; if only things were so obvious today.