Overview
The slogan arrived before the invasion did. By early 2003 "no blood for oil" was on placards in a dozen countries, and the claim it compressed — that the stated reasons for removing Saddam Hussein were cover for control of Iraqi reserves — has been argued about ever since.
What makes this one unusual is that most of the argument has been conducted openly, by participants, on the record. There is no shortage of quotations; the difficulty is that they do not agree with each other, and several of the most-cited ones were qualified by the people who said them.
What was said
Tony Blair addressed it directly on the BBC weeks before the invasion, calling the oil conspiracy theory one of the most absurd claims available once analysed.
Alan Greenspan, who had chaired the Federal Reserve for nearly two decades, wrote in his 2007 memoir that he was saddened it was politically inconvenient to acknowledge what everyone knew: that the Iraq war was largely about oil. The sentence travelled quickly. Greenspan then spent some time qualifying it, telling reporters that he had not been describing the administration's motive but his own view that removing Saddam would reduce the risk of disruption to oil supplies, and that securing supply was not what had driven the decision.
General John Abizaid, who had commanded US Central Command, told an audience at Stanford in 2007 that of course it was about oil.
So the record contains a flat denial from a head of government, an assertion from a senior military commander, and a former central banker who said it and then narrowed what he had said. Advocates on both sides quote selectively from this set, and can do so honestly.
The case that oil was the motive
The strongest version does not claim that anyone intended to seize oilfields outright. It argues that Iraq's reserves made it strategically distinct — that a state sitting on some of the world's largest proven reserves, outside the sanctions-and-containment framework the United States preferred, was a problem that would not have commanded the same attention had it exported something else.
Supporters point to the sequencing of postwar planning, to the early attention paid to the oil ministry and infrastructure, and to the drafting of a hydrocarbons law that would have opened the sector to foreign firms. They argue that a policy can be about oil in the sense that oil determines which countries matter, without any participant privately naming it as the reason.
The case against
The rebuttals come from more than one direction, which is often missed.
The official position was that the war concerned weapons of mass destruction, Iraqi non-compliance with inspections and, later, democratisation. Defenders of that account note that the invasion disrupted oil supply rather than securing it, that prices rose, and that American firms did not end up dominating Iraqi production — Chinese companies took a large share of the post-invasion contracts.
A separate objection comes from writers on the left, who argue that the oil explanation is too neat and lets the actual decision-making off the hook. On this view the war is better explained by ideology, by post-9/11 threat perception and by a belief in remaking the region than by a resource calculation nobody has produced evidence for. Scholarship in this vein has argued that the assumption oil must be seized to be obtained misreads how oil markets work: it is a commodity that sells to whoever pays, and controlling territory is an expensive way to buy it.
Where it stands
The most defensible summary is probably the least satisfying one. Oil is not absent from any serious account of why Iraq mattered to American strategy, and no serious account makes it the sole cause. Historians who reject the slogan still tend to accept that the region's importance is inseparable from what is under it; historians who accept the slogan rarely mean that a specific barrel-count was traded for a specific invasion.
The disagreement is about weight rather than presence, which is why two decades of documents have not resolved it and probably will not.