With the 5th anniversary of the invasion of Iraq upon us, we thought it an appropriate time to revisit the story of Iraq’s WMD, the phantom biological and chemical weapons that provided the rationale for going to war. In the new issue of Prospect, our assistant editor Tom Chatfield tells the story of the WMD diehards—the true believers who have not yet given up hope of convincing the world that Saddam Hussein oversaw a substantial WMD programme. This is a story of Russian and Syrian conspiracy, of underwater weapons bunkers, of midnight convoys of trucks transporting WMD over international borders. But it is also a story of the dangers of overreaction. While the WMD conspiracists are almost certainly wrong—Chatfield spent hours in correspondence and discussion with three of the most prominent, and found little evidence to corroborate their claims—we must be careful to avoid slipping into the belief that WMD do not continue to pose a serious threat to international peace and security. While Saddam, it turns out, did not have any WMD to speak of, there is ample evidence that he intended to resume his biological and chemical weapons programmes at some point. Meanwhile, in the middle east and elsewhere, nuclear proliferation remains a grave concern. The story of the AQ Khan network shows how a clandestine group can help the development of nuclear weapons in other countries, including rogue states like North Korea, and while Iran seems to have ceased pursuing nuclear weapons for now, it continues to enrich uranium that could be used for a bomb in future. A further dangerous consequence of the Iraqi WMD debacle is the weakening of public faith in intelligence services. In a world of terrorist threats, rogue states and WMD proliferation, intelligence will become an increasingly vital element of security policy. We must not let the failures of our intelligence agencies over Iraq—and possibly the misguided uses to which their intelligence was put—destroy our belief in the importance of their vigilance.