On 6th July 2016, Her Majesty’s Government published The Report of the Iraq Inquiry – the ‘Chilcot Inquiry’. Led by Sir John Chilcot, the investigation into the United Kingdom’s (UK) participation in the Iraq War found that it began before all diplomatic avenues had been exhausted, that the threat of Iraqi Weapons of Mass Destruction (WMDs) was presented with unjustified certainty, and that the legal basis for British military action was ‘far from satisfactory’.
The UK’s entry into the Iraq War occurred during the period in which the Ministry of Defence (MOD) prioritised Counter-Insurgency (COIN) capabilities over those designed for peer conflict. As the global geopolitical stage becomes increasingly volatile, however, there are still valuable insights to be gained from examining Britain’s involvement in the Iraq War. Therefore, for this week’s Big Ask, we asked six experts – as well as Gemini, Google’s Large Language Model (LLM): What are the lessons from the Chilcot Inquiry?
Richard Ballett
Council on Geostrategy
The publication of the Chilcot Inquiry was an important moment in British history. The document showed that Her Majesty’s Government exhibited deeply entrenched bureaucratic qualities that contributed to strategic blunders, such as informal, sofa government with a small group of like-minded and ill-informed individuals, poor information flows, and a culture of ‘winging it’ rather than conducting serious planning or analysis.
The key lessons are thus the importance of serious deliberation and sourcing alternative perspectives; the imperative of rigorous, impartial assessments that provide policymakers and elected leaders with an unvarnished picture of the truth; and the need to foster a culture of challenge where officials feel empowered to speak truth to those in power.
In my own civil service career, which started shortly after the Inquiry’s publication, I saw a lot of progress in rooting out these inimical pathologies. The UK’s intelligence assessment community has significantly improved its processes and capabilities over the last decade.
The creation of the Secretary of State’s Office of Net Assessment and Challenge (SONAC) at the MOD also played an important role, by providing leaders alternative perspectives and rigorous analysis to support some of the most consequential resource and budgetary prioritisation choices made in defence in recent years. From 2022-2024, SONAC acted as a lightning rod of challenge, empowered voices across the department, and forced leaders in defence to question their assumptions. The external appointment of Prof. John Bew as the Prime Minister’s Foreign Policy Adviser had the same impact on other matters of national security and diplomacy. These are just three examples of where things improved.
Ten years on, the real lesson from the Chilcot Inquiry is that Britain can never take for granted the positive changes that have been gained. Multiple and overlapping initiatives like those mentioned above can become self-reinforcing when sustained over long timeframes. However, momentum can also be lost when concurrent crises hit, when the wrong people are appointed to senior advisory positions, and when the memories of strategic blunders fade, causing bureaucracies to slip back into bad habits.
The challenges that the UK will face in the years ahead will be far more serious, complex, and numerous than those faced in the early 21st century. Adversaries today are far more powerful and dangerous than the tiny rogue states and terrorists that British leaders had to contend with in the 2000s. Consequently, the UK’s rivals will be able to exploit strategic blunders in ways that Osama bin Laden and Saddam Hussein could only have dreamed of.
Ten years after the publication of the Chilcot Inquiry, and with Britain about to see its seventh Prime Minister enter 10 Downing Street in less than a decade, it is more important than ever before that the UK’s leaders heed its lessons.
Brig. (rtd.) Rory Copinger-Symes CBE
Senior Adviser, Bondi Partners and SecureCloud+, and Non-Executive Director, Halo International Group
The Chilcot Inquiry’s main lessons, as I see them from a military perspective, are as follows:
Intelligence: WMD judgements were presented with unjustified certainty, the Joint Intelligence Committee (JIC) failed to maintain analytical distance, and ministers were not given sufficiently caveated assessments – the 45-minute claim being the obvious example. The lesson is not ‘do not trust intelligence’, but ‘do not let policy eagerness convert probabilistic intelligence into public certainty’.
Post-war planning: Planning assumed a well-executed United States (US)-led and United Nations (UN)-authorised operation in a relatively benign security environment. Phase 4 (Stabilisation) got a fraction of the attention that Phase 3 (Combat Operations) did – it was an afterthought.
Endstate definition: Commanders lacked clear direction on what ‘winning’ looked like post-Phase 3: warfighting, peacekeeping, COIN operations, or nation building? Objectives need explicit redefinition at phase transition, with commanders pushing back when that has not happened.
Civil-military integration: The split between MOD-led combat operations and a separate, under-resourced stabilisation effort meant security gains were not converted into governance gains. This fed directly into the establishment of the Stabilisation Unit and its associated doctrine, but the underlying lesson is that the military can win the fight and still lose the follow-through if civilian capacity is not resourced and integrated from day one.
Resourcing: The British Armed Forces spread themselves too thin between Iraq and Afghanistan, and were sharply criticised for their slow response to the Improvised Explosive Device (IED) threat, with the Snatch Land Rover being inadequate for the environment. Urgent operational requirements need to move fast, and admit that pre-war equipment assumptions were wrong.
The overarching lesson from the Chilcot Inquiry is: do not go to war on uncertain evidence, weak process, or without a credible plan for what comes next. Reforms alone will not fix this without genuinely challenging prevailing culture. However, the real question is whether any of this has actually been learned.
Distinguished Professor, Centre for Security, Diplomacy and Strategy, Brussels School of Governance, Vrije Universiteit Brussel
The most popular definition of ‘strategy’ seems to be that of Arthur Lykke: it is simply about ends, ways, and means. There is an equally simple – nay, a simplistic – assumption that this describes a process; that strategy is about first defining ends (what did the US want to achieve?), then identifying the means that are needed (assumption: the means exist or can be procured in time), and finally thinking about ways to apply them.
Reality is different, as the findings of the Chilcot Enquiry emphasise: ‘[Her Majesty’s] Government should not commit to a firm political objective [i.e., identify ends] before it is clear that it can be achieved [i.e., the means exist and ways align]’. Her Majesty’s Government was criticised for having accepted military responsibilities ‘without a robust analysis...of the military’s capacity to support the UK’s potential obligations in [Iraq]’, and whether ‘a step of such magnitude should [have been] taken…having considered the wider strategic and resource implications and contingent liabilities.’
Even key American strategist-practitioners recognise that this is the more realistic approach: Donald Rumsfeld, who listened to British-American strategist Colin S. Gray, famously noted that one goes to war with the armed forces one has, rather than the armed forces one wished one had. Lykke’s definition of strategy also does not mention the crucial dialectic with the enemy…
The lesson of the Chilcot Inquiry is that the ends, ways, and means approach should be laid to rest.
International Fellow, Council on Geostrategy, and Senior Vice President of National Security and Intelligence Programmes, Centre for the Study of the Presidency and Congress
Thematically, several of the most significant lessons woven throughout the Chilcot Inquiry (and the Butler Review) relate to the risks associated with the use and misuse of strategic intelligence in politics. A central failing of the Iraq War was the use of intelligence without its necessary caveats and acceptance of its limitations.
Much as intelligence professionals and politicians alike would wish to have an unfailing crystal ball, providing a palantír-like (the JRR Tolkien, not Alex Karp version) window into the thinking of adversaries, it simply does not exist. Raw intelligence is incomplete, muddled, and often contradictory. Absent its context and its origin (which often cannot be disclosed due to the risks to sources and methods), it offers only one piece of a much broader jigsaw puzzle; one for which there is no image on the box.
Moreover, as the Iraq War demonstrated, the desire to make a compelling case to justify a chosen course of action led to the manipulation and cherry-picking of intelligence to fit predetermined narratives. There was far too much twisting of data to support theories, not theories to fit data. Today, and consequently, the British intelligence community is a much-changed entity using a single common language for interpretation, providing analysis and not raw intelligence to politicians, and internally stress testing assumptions and analysis.
The run-up to Russia’s expanded offensive in Ukraine was a much different affair. Washington and London used (declassified) strategic intelligence, seeking to signal publicly that both capitals knew what the Kremlin was planning and to communicate the imminent threat to sceptical allies across Europe, as well as into Ukraine.
While the selective use of strategic intelligence (which certainly benefited from open-source intelligence) neither deterred Russia, nor convinced even Volodymyr Zelenskyy, President of Ukraine, of the risk to his country, it was nonetheless used with far more aplomb in 2022 than in 2003.
Honorary Fellow, Council on Geostrategy, and Director, Oxford Strategy, Statecraft, and Technology (Changing Character of War) Centre
Much of the commentary on the anniversary of the Chilcot Inquiry will focus on the extent to which His Majesty’s (HM) Government has adhered to the principle that all policy decisions should be subject to ‘constructive challenge’ – that is, that subordinates should be willing to offer a critical review and test assumptions without fear of accusations of disloyalty. The imperative was to avoid hasty, ill-thought through, and erroneous decisions.
The track record of British governments has not lived up to that expectation. Ministerial dependence on Special Advisers (SpAds), a focus on spin or ‘narratives’, and a lack of specialisms or incentives in the civil service are the chief problems. However, the idea of accountability upwards is only part of the story.
In one respect, the failure of accountability downwards also remains. In Iraq, many soldiers were wrongly accused of war crimes by the Iraq Historic Allegations Team (IHAT) inquiry. Not a single case led to a conviction, and the investigation revealed that the lawyers responsible were inventing accusations for profit. The same approach is being taken against British veterans deployed in Northern Ireland in the so-called Troubles Bill.
It is a reminder that loyalty goes in both directions. Regrettably, that lesson has not been learned.
Co-President (Research), Council on Geostrategy
The Chilcot Inquiry provided a damning indictment of the 2003 Iraq War, offering enduring lessons on flawed intelligence, institutional groupthink, and the erosion of Cabinet scrutiny. One of its core conclusions – that HM Government must adhere to international law – rightly sought to curb erratic, badly planned interventions. Yet, subsequent British foreign policy has suffered from a severe overcorrection. The lesson of legality has morphed into a dogmatic legalism that blindfolds strategic realism.
Nowhere is this paralysis more evident than in the decision (now failed) to cede sovereignty of British Indian Ocean Territory, including the vital joint UK-US military facility at Diego Garcia, to Mauritius. Driven by a desire to conform to non-binding international decisions, HM Government attempted to trade away one of Britain’s geopolitical crown jewels. In an era defined by a fracturing international order and growing alignment between the CRINK – the People’s Republic of China, Russia, Iran and North Korea – such compliance does not project moral authority; rather, it weakens the UK and invites others to make claims on British interests.
Per Chilcot, this is not to say that the UK should ignore international law. While poorly planned interventions should be resisted, a mature foreign policy – underpinned by the pursuit of strategic and asymmetric advantage, as per the 2025 National Security Strategy – demands a balance between legal frameworks and cold strategic realities. If HM Government fails to maintain this equilibrium, rigid adherence to international law will cease to be a shield, becoming instead an open invitation for geopolitical adversaries. Even Chilcot’s lessons should not go unchallenged.
Gemini
Council on Geostrategy staff have prompted Gemini, Google’s LLM, to reflect on this week’s Big Ask.
The Chilcot Inquiry remains the definitive critique of British strategic decision-making, offering enduring lessons for contemporary British statecraft as it navigates an increasingly contested Euro-Atlantic and Indo-Pacific landscape.
First, it exposed the dangers of insular thinking. The Inquiry revealed how intelligence was presented with unwarranted certainty and left unchallenged. For modern policymakers, fostering a culture of rigorous, adversarial debate – where alternative assessments and dissenting views are integrated – is paramount to avoiding critical blind spots.
Second, it underscored that formal cabinet governance is non-negotiable. The informal style of the era bypassed established bureaucratic mechanisms, undermining collective ministerial responsibility and reducing vital scrutiny. Effective geostrategy requires robust, institutionalised decision-making, a lesson that later informed the creation of the National Security Council (NSC).
Finally, its most damning indictment was the failure of post-conflict planning. The UK committed to military intervention without a coherent, fully resourced strategy for stabilisation and reconstruction. It proved that military force is merely an instrument; without a clear endgame, tactical operational successes quickly dissolve into long-term strategic failures.
Ultimately, the Chilcot Inquiry’s core lesson is that successful statecraft demands intellectual humility, institutional rigour, and a realistic alignment of military means with sustainable political ends.
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