As the United States prepared to invade Iraq in 2003, the Department of Defense issued a set of guidelines that would change the way American news organizations covered war. The new rules established an embed system, under which roughly 500 journalists would live, eat, travel, and experience combat with invading US troops.

The system represented the latest attempt to mitigate the tension between transparency and security that had long bedeviled the presss relationship to the military. During World War I and World War II, the balance tipped toward securitythe press for the most part assented to an official policy of censorship that among other things banned images of dead or wounded American soldiers. During the Vietnam War, by contrast, the military exerted little official control over where journalists could go and what they could publish. But as the war dragged on and battlefield photographs, dispatches, and body counts increasingly conflicted with official assurances of imminent victory, the press and the military developed a mutual mistrust that endured far beyond the end of the conflict. During later US wars in Panama and Grenada, members of the press were tethered to military bases until most of the fighting had stopped.

The new embed system was an expansion of a similar system the US military had first tried during its first war in Iraq, in 1991. Then, a handful of journalists were permitted to accompany invading troops and share among participating news organizations reports and photographs they gathered in the battlefield. Some journalists also operated as what the military called unilaterals, traveling about the war zone without military restrictionsor military protection. In theory such independence gave a journalist the opportunity to see and report on what the military might decline to show them. In practice, the work was exceedingly difficult and dangerous, starting with the logistical problems of entering a war zone in the first place. The press and the military achieved similarly ad hoc accommodations in later US engagements in Somalia, Bosnia, Kosovo, and Afghanistan.

Listen to AP Director of Photography Santiago Lyon discuss the evolution of the embed and pool system.