Sleep deprivation for over a week, beatings, shackling, and waterboarding - a grim litany of the cruel methods used by the Bush-era CIA to interrogate al Qaeda terror suspects was exposed in a report on Tuesday.
The shocking report released by the US Senate found that the techniques employed by the Central Intelligence Agency were "far more brutal" than the spy agency had previously admitted to.
It was drawn up over several years by the Senate intelligence committee, which revealed such techniques were applied with "significant repetition for days or weeks at a time" on prisoners rounded up in the "war on terror" launched after the 2001 terror attacks on the United States.
The worst treatment was meted out at a secret CIA detention site dubbed COBALT where "unauthorized" interrogation techniques were used in 2002.
Slaps and 'wallings'
Beginning with the CIA's first high-value al Qaeda detainee Abu Zubaydah, suspects were routinely slammed against a wall by their interrogators and hit with rolled-up towels.
Facial slaps, or "insults," as well as stomach punches were also used.
The interrogators also used "attention grasps" in which the prisoner is grabbed with both hands, one on each side of the collar and pulled towards the interrogator.
This involved keeping detainees awake for up to 180 hours, or more than a week, usually standing or in stress positions, sometimes with their hands shackled above their heads, chained to the ceiling.
Abu Zubaydah was kept in an all-white room that was lit 24 hours a day. Or he was kept awake by non-stop questioning.
At least five detainees suffered "disturbing hallucinations" but in at least two cases the CIA continued with the interrogation method.
Confinement and isolation
Over 20 days, Abu Zubaydah spent 266 hours (11 days, 2 hours) in a large coffin-size box, and 29 hours in an even smaller one during his interrogation at what was dubbed Detention Site Green.
In the COBALT facility, dubbed a "dungeon" by the chief of interrogations, prisoners were kept in complete darkness, often shackled with their hands above their heads and mainly nude.
They were bombarded with loud music and noise and given a bucket as a toilet. In 2002 a prisoner who had been partially nude and chained to a concrete floor died of suspected hypothermia.
Ice water baths or showers were also used to try to break suspects.
Some detainees were also forced to wear diapers, although guidelines said they could not be left on longer than 72 hours.
This was used at the COBALT facility. About five CIA agents would scream at a detainee, drag him outside his cell, cut his clothes off and wrap him in duct tape.
He would then be hooded and dragged up and down a dirt hallway while being slapped and punched.
After his death at the COBALT site, Gul Rahman was found to have been covered with bruises and abrasions on his shoulders, pelvis, arms, legs and face.
Prisoners were often stripped and left nude in their cells. Zubaydah was kept naked but given a towel to cover himself during interrogations. Abd al-Rahim al-Nashiri, the alleged mastermind of the 2000 attack on the USS Cole, was often naked during his grillings. But at one point he was given clothes when he was wracked by shivering due to a head-cold.
CIA officers regularly threatened the detainees. One was told he would only leave the facility in "a coffin-shaped box."
At least three detainees were told the CIA would hurt their families, including their children.
There was a threat to sexually abuse the mother of one, while another was told his mother's throat would be cut. The methods were supposed to ensure prisoners developed a sense of "Learned helplessness."
Nashiri was blindfolded and a pistol was placed near his head, while a CIA officer also operated a cordless drill near his body in a macabre game of Russian roulette.
Forced rectal feeding
At least five prisoners were subjected to "rectal rehydration or rectal feeding without documented medical necessity," the report said.
Other detainees were given a liquid diet of protein drinks known as Ensure "as a means of limiting vomiting during waterboarding."
In this technique of previously described "near drownings," the detainee was bound to an inclined bench with his feet usually raised.
A cloth is placed over the forehead and eyes and water is then poured in a controlled way onto the clothing. The cloth is then lowered over the nose and mouth.
Once the cloth is saturated, the prisoner's flow of air is restricted for up to 40 seconds while the cloth is left in place over the nose and mouth.
The self-confessed mastermind of the 9/11 attacks, Khalid Sheikh Mohammed, is known to have been waterboarded 183 times.
In March 2003 he was subjected to five waterboard sessions over 25 hours.
"The waterboarding technique was physically harmful, inducing convulsions and vomiting," the report said.
In July 2002, the attorney general verbally approved putting Zubaydah in a box with an non-stinging insect because he is afraid of them. It was not clear from Tuesday's summary though if this technique was actually used.
Spy agency faces backlash
US President Barack Obama declared some of the past practices to be "brutal, and as I've said before, constituted torture in my mind. And that's not who we are," he told the Spanish-language TV network Telemundo in an interview.
Obama said releasing the report was important "so that we can account for it, so that people understand precisely why I banned these practices as one of the first acts I took when I came into office, and hopefully make sure that we don't make those mistakes again."
Republican Senator John McCain, tortured in Vietnam as a prisoner of war, was out of step with some fellow Republicans in welcoming the report and endorsing its findings.
"We gave up much in the expectation that torture would make us safer," he said in a Senate speech. "Too much."
Five hundred pages were released, representing the executive summary and conclusions of a still-classified 6,700-page full investigation.
Sen. Dianne Feinstein, the Democratic committee chairman whose staff prepared the summary, branded the findings a stain on US history.
"Under any common meaning of the term, CIA detainees were tortured," she declared, commanding the Senate floor for an extended accounting of the techniques identified in the investigation.
In a statement, CIA Director John Brennan said the agency made mistakes and has learned from them.
But he also asserted the coercive techniques "did produce intelligence that helped thwart attack plans, capture terrorists and save lives."
In Geneva, the United Nations' special rapporteur on human rights and counter-terrorism, Ben Emmerson, said, the report confirms "that there was a clear policy orchestrated at a high level within the Bush administration, which allowed to commit systematic crimes and gross violations of international human rights law."
He said international law prohibits the granting of immunity to public officials who have engaged in acts of torture, including both the actual perpetrators and senior government officials who authorized the policies. "The individuals responsible for the criminal conspiracy revealed in today's report must be brought to justice, and face criminal penalties commensurate with the gravity of their crimes."
The report, released after months of negotiations with the administration about what should be censored, was issued as US embassies and military sites worldwide strengthened security in case of an anti-American backlash.
The US embassies in Afghanistan, Pakistan and Thailand warned of the potential for anti-American protests and violence after the release of the Senate report. The embassies also advised Americans in the three countries to take appropriate safety precautions, including avoiding demonstrations.