RABAT, Morocco - The assignments arrive on slips of paper, each bearing the black flag of the Islamic State, the seal of the terrorist group's media emir, and the site of that day's shoot.

"The paper just gives you the location," never the details, said Abu Hajer al Maghribi, who spent nearly a year as a cameraman for the Islamic State. Sometimes the job was to film prayers at a mosque, he said, or militants exchanging fire. But, inevitably, a slip would come with the coordinates to an unfolding bloodbath.

For Abu Hajer, that card told him to drive two hours southwest of the Syrian city of Raqqa, the capital of the caliphate, or Islamic realm, declared by the militant group. There, he discovered that he was among 10 cameramen sent to record the final hours of more than 160 Syrian soldiers captured in 2014.

"I held my Canon camera," he said, as the soldiers were stripped to their underwear, marched into the desert, forced to their knees and massacred with automatic rifles.

His footage quickly found a global audience, released online in an Islamic State video that spread on social media and appeared in mainstream news coverage on Al Jazeera and other networks.

Abu Hajer, who is now in prison in Morocco, is among more than a dozen Islamic State defectors or members in several countries who provided detailed accounts to the Washington Post of their involvement in, or exposure to, the most potent propaganda machine ever assembled by a terrorist group.

What they described resembles a medieval reality show. Camera crews fan out across the caliphate every day, their ubiquitous presence distorting the events they purportedly document. Battle scenes and public beheadings are so scripted and staged that fighters and executioners often perform multiple takes and read their lines from cue cards.

Cameras, computers, and other video equipment arrive in regular shipments from Turkey. They are delivered to a media division dominated by foreigners - including at least one American, according to those interviewed - whose production skills often stem from previous jobs they held at news channels or technology companies.

Senior media operatives are treated as "emirs" of equal rank to their military counterparts. They are directly involved in decisions on strategy and territory. They preside over hundreds of videographers, producers and editors who form a privileged, professional class with status, salaries and living arrangements that are the envy of ordinary fighters.

"It is a whole army of media personnel," said Abu Abdullah al Maghribi, a second defector who served in the Islamic State's security ranks but had extensive involvement with its propaganda.

"The media people are more important than the soldiers," he said. "Their monthly income is higher. They have better cars. They have the power to encourage those inside to fight and the power to bring more recruits to the Islamic State."

Increasingly, that power extends beyond the borders of the caliphate. The attacks in Paris were carried out by militants who belonged to a floating population of Islamic State followers, subjects who are scattered among dozens of countries and whose attachments to the group exist mainly online.

Abdelhamid Abaaoud, the alleged architect of the attacks who was killed in a raid in France, had appeared repeatedly in Islamic State recruiting materials. The barrage of videos and statements released afterward made clear that the overriding goal of the Islamic State is not merely to inflict terror on an adversary but also to command a global audience.

The United States and its allies have found no meaningful answer to this propaganda avalanche. A State Department program to counter the caliphate's messaging has cycled through a series of initiatives with minimal effect. Islamic State supporters online have repeatedly slipped around efforts to block them on Twitter and Facebook.

Overmatched online, the United States has turned to lethal force. Recent U.S. airstrikes have killed several high-level operatives in the Islamic State's media division, including Junaid Hussain, a British computer expert. FBI Director James B. Comey recently described the propaganda units of the Islamic State, also known as ISIL or ISIS, as military targets.

"I am optimistic that the actions of our colleagues in the military to reduce the supply of ISIL tweeters will have an impact," Comey said at an event last month in Washington. "But we'll have to watch that space and see."

Research for this article involved interviews with Islamic State defectors and members, as well as security officials and counterterrorism experts in six countries on three continents. The most authoritative accounts came from seven Islamic State defectors who were either in prison in Morocco or recently released after facing terrorism charges upon their return from Syria. All spoke on the condition that they be identified only by the adopted names that they used in Syria.

Those interviews were conducted with the permission of the Moroccan government in a prison complex near the nation's capital. The prisoners said they spoke voluntarily after being approached by Moroccan authorities on behalf of the Post. Other prisoners declined. Most of the interviews took place in the presence of security officials, an arrangement that probably led participants to play down their roles in the Islamic State but seemed to have little effect on their candor in describing the caliphate's media division.

Abu Hajer, a soft-spoken Moroccan with a thin beard and lean physique, said he had been active in jihadist media circles for more than a decade before he entered Syria in 2013. He began participating in online Islamist forums after the U.S. invasion of Iraq in 2003, he said, and later became an administrator of an influential site known as Shamukh, giving him authority to admit new members and monitor the material other militants posted.

Those credentials cleared his path to coveted assignments within the Islamic State, a group that began as al-Qaeda's affiliate in Iraq before splitting off from that terrorist network in an ideological rupture two years ago.

The group has an elaborate system for evaluating and training new arrivals. Abu Hajer said that shortly after entering Syria he was groomed to be part of the Islamic State's media team. He spent two months undergoing basic military training before he was admitted to a special, monthlong program for media operatives.

The program "specializes in how to do filming. How to mix footage. How to get the right voice and tone" in interviews, he said. After completing the course, he was given a Canon camera, a Samsung Galaxy smartphone and an assignment with the caliphate's media unit in Raqqa. Why did victims in Islamic State beheading videos look so calm? They didn't know it was real.

Abu Hajer, who is in his mid-30s, had come from an impoverished corner of Morocco. Now that he is in prison, his wife and children have returned to the encampment where they lived before departing, a shanty village of corrugated tin and plywood with no running water near a cement plant on the outskirts of Rabat.

In Syria, they were given a villa with a garden. Abu Hajer was issued a car, a Toyota Hilux with four-wheel drive to enable him to reach remote assignments. He was also paid a salary of $700 a month - seven times the sum paid to typical fighters - plus money for food, clothes and equipment.

Abu Hajer said he had grave objections to what happened to the Syrian soldiers in the massacre that he filmed in the desert near Tabqa air base. But he acknowledged that his misgivings had more to do with how the soldiers were treated - and whether that comported with Islamic law - than any concern for their fates.