ISLAMABAD » They are dead men talking, and they know it. Gulping nervously, the prisoners stare into the video camera, spilling tales of intrigue, betrayal and paid espionage on behalf of the United States. Some speak in trembling voices, a glint of fear in their eyes. Others look resigned. All plead for their lives.

"I am a spy and I took part in four attacks," said Sidinkay, a young tribesman who said he was paid $350 to help direct CIA drones to their targets in Pakistan’s tribal belt. Sweat glistened on his forehead; he rocked nervously as he spoke. "Stay away from the Americans," he said in an imploring voice. "Stay away from their dollars."

Al-Qaida and the Taliban have few defenses against the U.S. drones that endlessly prowl the skies over the bustling militant hubs of North and South Waziristan in northwestern Pakistan, along the Afghan border. CIA missiles killed at least 246 people in 2012, most of them Islamist militants, according to watchdog groups that monitor the strikes. The dead included Abu Yahya al-Libi, the al-Qaida ideologue and deputy leader.

Despite the technological superiority of their enemy, however, the militants do possess one powerful countermeasure.

For several years now, militant enforcers have scoured the tribal belt in search of informers who help the CIA find and kill the spy agency’s jihadist quarry. The militants’ technique — often more witch hunt than investigation — follows a well-established pattern. Accused tribesmen are abducted from homes and workplaces at gunpoint and tortured. A sham religious court hears their case, usually declaring them guilty. Then they are forced to speak into a video camera.

The taped confessions, which are later distributed on CD, vary in style and content. But their endings are the same: execution by hanging, beheading or firing squad.

In Sidinkay’s last moments, the camera shows him standing in a dusty field with three other prisoners, all blindfolded, illuminated by car headlights. A volley of shots rings out, and the three others are mowed down. But Sidinkay, apparently untouched, is left standing. For a tragic instant, the accused spy shuffles about, confused. Then fresh shots ring out and he, too, crumples to the ground.

These macabre recordings offer a glimpse into a little-seen side of the drone war in Waziristan, a paranoid shadow conflict between militants and a faceless American enemy in which ordinary Pakistanis have often become unwitting victims.

Outside the tribal belt, the issue of civilian casualties has dominated the debate about U.S. drones. At least 473 noncombatants have been killed by CIA-directed strikes since 2004, according to monitoring groups — a toll frequently highlighted by critics of the drones like Pakistani politician Imran Khan. Still, strike accuracy seems to be improving: just seven civilian deaths have been confirmed in 2012, down from 68 the previous year, according to the Bureau of Investigative Journalism, which has been critical of the Obama administration’s drone campaign.

And civilian lives are threatened by militants, too. As the U.S. campaign has cut deeply into the commands of both the Taliban and al-Qaida, drone-fearing militants have turned to the local community for reprisals, mounting a concerted campaign of fear and intimidation that has claimed dozens of lives and further stressed the already fragile order of tribal society.

The video messages from accused spies are intended to send a stark message, regardless of whether innocents are among those caught up in the deadly dragnet. The confessions are delivered at gunpoint, and usually follow extensive torture, including hanging from hooks for up to a month, human rights groups say.

"In every civilized society, the penalty for spying is death," said a senior commander with the Pakistani Taliban, speaking on the condition of anonymity from Waziristan.

Although each myriad militant faction in Waziristan operates its own death squads, by far the most formidable is the Ittehad-e-Mujahedeen Khorasan, a shadowy group that experts consider to be al-Qaida’s local counterintelligence wing. Since it emerged in 2009, the group, which is led by Arab and Uzbek militants, has carefully cultivated a sinister image through video theatrics and the ruthless application of violence.

Black-clad Khorasan militants, their faces covered in balaclavas, roam across North Waziristan in jeeps with tinted windows. In one video clip from 2011, Khorasan fighters are seen searching traffic under a cluster of palm trees outside Mir Ali, a notorious militant hub. Then they move into the town center, distributing leaflets to shoppers, before executing three men outside a gas station.

"Spies, your days are numbered because we are carrying out raids," chants the video soundtrack.

Thought to number dozens of militants, the Khorasan cooperates closely with Afghan warlord Jalaluddin Haqqani, who is based in North Waziristan. A sister organization in Afghanistan has been responsible for 250 assassinations and executions, according to U.S. military intelligence.

"Everyone’s frightened of them," said Mustafa Qadri of Amnesty International, which recently published a report on human rights abuses by both the military and militants in the tribal belt. "No one really knows who is behind them. But they are very professional."

The videotapes produced by Khorasan and other groups offer a stark, if one-dimensional, picture of their spy hunt. A review of 20 video confessions by The , as well as interviews with residents of the tribal belt, suggest the suspects are largely poor tribesmen — barbers, construction workers, Afghan migrants.

The jittery accounts of the accused men reveal dramatic stories of espionage: furtive meetings with handlers; disguising themselves as Taliban fighters, fruit sellers or even heroin addicts; payment of between $150 and $450 per drone strike; and placing American-supplied electronic tracking devices, often wrapped in cigarette foil, near the houses and cars of al-Qaida fugitives.

But the videos are also portraits of fear and confusion, infused with poignant, even darkly comic, moments. Curiously, some say they have been hired through Pakistani military intelligence officials who are identified by name, directly contradicting the Pakistan government’s official stance that it vehemently opposes the drone strikes. An official with Inter-Services Intelligence, speaking on the customary condition of anonymity, said any suggestion of Pakistani cooperation was "hogwash."

Quite clearly, the video accounts are stage-managed. Behind the camera, an unseen militant prompts the prisoners to speak. Some say they have been told they will be freed if they tell the "truth." Others are preparing for death. "Tell my parents that I owe 250 rupees to a guy from our village," Hamidullah, a bearded Afghan migrant, said in a quavering voice. "After I die, please repay the money to him."

Death is not inevitable, however. Suleman Wazir, a 20-year-old goat herder from South Waziristan, said militants abducted him in September on suspicion of being a spy.

"They held me in a dungeon and flogged me hundreds of times. They told me I would die," he said in a video interview recorded through an intermediary in Waziristan. But after some weeks, Wazir said, his relatives intervened through tribal elders and persuaded the Taliban of his innocence. Upon presentation of five goats to the militants, he was set free, he said.

The Taliban and al-Qaida have become obsessed with "patrai" — a local word for a small metallic device, now synonymous with the tiny electronic tagging devices that militants believe the CIA uses to find them. In 2009 Libi, the al-Qaida deputy, published an article illustrated with photographs of such devices, warning of their dangers. He was killed in a drone strike near Mir Ali in June.

This year the Taliban released a video purporting to show one such device: an inchlong electronic circuit board, cased in transparent plastic, that, when connected to a 9-volt battery, pulsed with an infrared light. A spokesman for the CIA declined to comment on details of the drone program. But a former American intelligence official, speaking on the condition of anonymity, confirmed that the agency does use such GPS devices, which are commercially available in the United States through stores that supply the military.

As a result, the Taliban are adapting. Wali ur-Rehman, a senior Taliban commander, said in an interview last spring that his fighters had started to scan all visiting vehicles with camcorders set to infrared mode in order to detect potential tracking devices.

Still, the Taliban may be overestimating the importance of such devices. A former Obama administration official, speaking on the condition of anonymity because of the classified nature of the subject, said that satellites and aerial surveillance planes — whose powerful sensors sweep up mobile phone, Internet and radio intercepts from the tribal belt — provide much of the drone program’s electronic intelligence. Other experts said many American intelligence informers in Waziristan are recruited in Afghanistan, where a CIA base in the border province of Khost was attacked by a suicide bomber three years ago.

On the ground, though, the spy war has further destabilized a tribal society already dangerously weakened by years of violence. Paranoia about the profusion of tracking chips has fueled rivalries between different clans who accused one another of planting the devices.

"People start to think that other tribes are throwing the chips. There is so much confusion and mistrust created within the tribal communities. Drone attacks have intensified existing mistrust," one tribesman told researchers from Columbia Law School, as part of a study into the effects of the drone campaign, last May.

The Khorasan’s brutality has alienated even some of its putative allies. In September 2011, Hafiz Gul Bahadur, a leading warlord in North Waziristan, publicly withdrew his support for the group after coming under pressure from tribal supporters over the number of apparently innocent tribesmen who had been executed as spies. In a statement, the Khorasan responded that would pursue its objectives "at all costs and not spare anyone."

Amid the long knives and paranoia, some tribesmen believe there is no option but to flee. Some of those accused of espionage run to the gulf states; others make it to the sprawling slums of the port of Karachi. In an ethnic Pashtun neighborhood of that city, one elderly man described how he fled with his family after the execution of his son in 2009.

"I was afraid the militants would also kill me and my family," said the man, speaking on the condition of anonymity.

Still now, his life remained in danger, he added, because the Taliban believed he was spending what they said was his son’s ill-gotten money. But it was simply untrue, the old man insisted: "My son was innocent."

© 2012 The New York Times Company