Allegations that American military analysts may have “cooked the books” to skew intelligence assessments about the campaign against the Islamic State (IS) group, providing a more optimistic account of progress than in fact has been made, are a sign of bad things to come. Bad intelligence leads to bad decisions. When purposely manufactured or manipulated it suggests a war that is being lost, with the people in charge loathe to admit it even as they continue to stumble forward, ever-more blindly. And if that sounds like America's recent war in Iraq, or its earlier one in Vietnam, this is not so very far from the truth. A US Pentagon inspector general's investigation into allegations of overly optimistic intelligence reporting, first reported in the New York Times, began after at least one US Defence Intelligence Agency analyst claimed officials overseeing the war against IS were improperly reworking the assessments prepared for senior policy-makers. The focus is on whether military officials changed the conclusions of draft intelligence assessments during a review process and then passed them on. Intelligence typically involves working with incomplete data (one analyst likens the process to turning over a small subset of rocks in a large field) in order to assess the present situation and then to predict the future. Anyone who claims to be certain about the future is more likely to be a fortune-teller than a professional analyst, and so it is quite reasonable and common for a group of honest, well-meaning people to assess a data set and come to different conclusions. To be of value, however, legitimate differences of opinion must be played off against one another in a non-politicised, intellectually vigorous check-and-balance fashion, as enshrined in US Intelligence Community Directive 203. There is a wide gap between that and what it appears the Pentagon inspector general is now looking into. We can assume that the inspector general knows a legitimate difference of opinion when he sees one, can easily rule out a sloppy supervisor, or spot a mid-level official rewriting things to pump up his own credentials. Investigations of the level leaked to the New York Times are not needed to deal with such situations. What appears to be under the microscope is whether or not the intelligence assessments headed to senior US policy-makers were purposely inaccurate. Cooking intelligence also has a sordid history in the annals of American warfare. Former CIA analyst Paul Pillar described the process in a post-mortem report on the 2003 Iraq intelligence failures, noting that “intelligence analysts and their managers knew that the United States was heading for war with Iraq. It was clear that the Bush administration would frown on or ignore analysis that called into question a decision to go to war and welcome analysis that supported such a decision.” Those factors led directly to the flawed if not outright fraudulent 2002 US National Intelligence Estimate (NIE) that supported the narrative of weapons of mass destruction in Iraq. The NIE was used by the White House to press Congress into supporting war, and by then-US Secretary of State Colin Powell to do the same at the United Nations. The so-called “Downing Street Memo” issued in the UK also bluntly stated that “the intelligence and facts were being fixed around the policy” in the lead-up to the 2003 war in Iraq. Analysis during the Vietnam War also pushed forward a steady but false narrative of victory. Former CIA and US army analyst Patrick Eddington notes that analysts' conclusions that the US would be unlikely to ever defeat North Vietnamese forces were repeatedly overruled by commanders certain that the United States was winning. He cites a complex inter-agency process of manipulating data to match the needs of US General William Westmoreland's narrative that enemy morale and military structure were deteriorating. The CIA's Paul Pillar also stresses the difficulties of dissent and of speaking truth to power when he writes, “You're part of a large structure that does have a vested interest in portraying the overall mission as going well.” Compare that to what any journalist, graduate student or successful businessperson should be able to tell you, which is that information must drive conclusions, not the reverse. The more complex the problem, the higher the quality of information needed to solve it. The situation with IS is more complex than that faced by the United States in Iraq over a decade ago, or in Vietnam before that. IS is a trans-state, loosely organised fighting force whose defeat requires the United States to stitch together a collection of strange bedfellows, each with its own agenda, in the hope that the sum will add up to victory. The Iranians support Iraq's Shiite militias against IS, but not Iraq's Sunni forces. Turkey is prepared to wage war only in equal dollops against America's IS enemies and America's allies, the Kurds. The Kurds themselves fight well in their own territories but are loathe to strike elsewhere in Iraq. Creating a unified strategy out of all this demands hard objective reporting and courageous analysis. There are three positions on why the US military might not be providing such courageous analysis and instead substituting a more positive spin on events. The first is basic bureaucratic cover: saying things are going well is a neat way of telling the boss that the military is doing the job they were sent to do and a self-administered pat on the back. Such thinking should never be easily discarded. However, higher-ups in the military chain of command will eventually look askance at such tactics, fearful of blow-back if events on the battlefield turn sour. The second position is of more concern. Imagine a scenario where the US president is rejecting advice from his generals to continue the war against IS and wants to reduce the level of American involvement (as some say US President John F Kennedy wished to do in Vietnam before his assassination). The president pushes back, saying nothing has worked and that ongoing failure comes at great cost. A military that wishes to stay engaged, again as in Vietnam, might want to create the appearance that current levels of involvement are good, and thus increased involvement will be even better. But it is the third position, reporting only the good news that senior policy-makers signal they want to hear, that history suggests is the dominant reason. If American military intelligence insists on pushing false narratives of progress up the chain of command, this strongly suggests that someone higher up, afraid of the truth, is happy to receive only the palliative of good news. And that is bad news. The lessons of modern history make it clear that misleading policy-makers who themselves seek to be misled can only yield disastrous consequences. The writer is a retired 24-year veteran of the US Department of State and author of We Meant Well: How I Helped Lose the Battle for the Hearts and Minds of the Iraqi People.