Iraq has proven to be a crucible in which US intelligence, and the CIA in particular, was tested over and again. The operations of the CIA and its sister services in and concerning Iraq have demonstrated their impressive capabilities, but also the limits of their reach. The high points include the detail with which the US intelligence community (USIC) profiled the Iraqi army before and during Operation Desert Storm, in 1991. The USIC's satellites and technical sensors, combined with the all-source intelligence fusion of CIA and other agency analysts, provided allied forces with a hitherto unprecedented level of insight into the locations, disposition and strength of the opposing forces, the difficulty encountered in disseminating this information down to tactical commanders notwithstanding. The low points included the long-term weakness in gathering intelligence on, and correctly assessing the nature of, erstwhile Iraqi dictator Saddam Hussein's weapons of mass destruction programmes. This was clearly underlined both in the assessments of Saddam's nuclear capabilities in the late 1980s and before the Persian Gulf War, which underestimated the progress and strength of his programme, and a decade later in the intelligence estimates preceding the 2003 Iraq War, which overestimated his capabilities. The second Gulf War (2003) and the subsequent investigations into the intelligence failures that surrounded it have resonated as one of the most significant and painful episodes in the CIA's history.

Both successes and failures relate to the struggle US intelligence grappled with over the years of the Cold War, namely the challenge of spying on closed, secure and secretive authoritarian and police states, and the solutions it found to the problem. These solutions were often based on technical means of peeking in from the outside. A variety of sensors – including aircraft, satellites, radar stations and even submarines – intercepted and collected all manner of communications, telemetry, signature and imagery intelligence from behind the Iron Curtain. This was melded with the more limited volume of human intelligence and open-source reporting that was available to allow the US to gauge the strength, readiness and leadership of the Soviet military. The results were not always perfect. But technical sources offered the West a competent understanding of Soviet military capabilities from fairly early in the Cold War.