This article contains illustrations some readers may find upsetting. Peter Bergen is CNN's national security analyst, a vice president at New America and a professor of practice at Arizona State University. His new book is "Trump and His Generals: The Cost of Chaos." The opinions expressed in this commentary are his own. View more opinion articles at CNN.

These drawings show the coercive interrogation techniques that Abu Zubaydah says were used on him by CIA interrogators when he was held in CIA secret prisons outside the US for four years after he was captured in Pakistan in 2002. It's one thing to read about these coercive techniques, but it's quite another to see Abu Zubaydah's sketches of these alleged techniques, which were obtained by CNN.

Abu Zubaydah's drawings show him:

The CIA declined to comment on these allegations of mistreatment by Abu Zubaydah.

According to Abu Zubaydah, the CIA used these techniques on him after he was captured in 2002. At the time he was believed to be a senior leader of al Qaeda. A number of these techniques were noted in the Senate Intelligence Committee's unclassified 2014 report on the CIA's interrogation program, including "walling," cramped confinement, stress positions, the use of insects and waterboarding.

In fact, it turned out Abu Zubaydah was a travel facilitator for the terrorist group, not one of its senior leaders. Indeed, Abu Zubaydah has never been charged with a crime and has been held at the Guantanamo Bay prison since 2006 without charge. As I documented in my 2011 book, "The Longest War: The Enduring Conflict Between America and al-Qaeda," Abu Zubaydah was captured in a shoot-out in Faisalabad, Pakistan, in March 2002 and was later interrogated by the CIA.

As I wrote in "The Longest War," paraphrased here:

Abu Zubaydah, whose real name is Zayn al- Abidin Muhammad Husayn, was the first prisoner to be placed in a secret overseas CIA prison in Thailand. There Ali Soufan , an Arabic-speaking FBI agent, interrogated him. Soufan softened up Abu Zubaydah by calling him "Hani," the childhood nickname his mother had used for him, a fact that he had gathered from intelligence files.

The approach started yielding quick results. When Abu Zubaydah was shown a series of photos of al Qaeda members by Soufan, he identified Khalid Sheikh Mohammed as "Mukhtar," meaning "the chosen" in Arabic.

This was a key to unraveling one of the great mysteries of the attacks on New York and Washington, because on a videotape recovered by American forces in Afghanistan a few months after 9/11, Osama bin Laden had referred to a "Mukhtar" as someone who had some sort of a plan for a "tall building in America."

Abu Zubaydah had now identified Mukhtar to be Khalid Sheikh Mohammed. Abu Zubaydah's confirmation of Mohammed's role in 9/11 was the single most important piece of information uncovered about al Qaeda after the attacks on the World Trade Center and Pentagon, and it was discovered during a standard interrogation, without recourse to any form of coercion.

Around 10 days after Soufan had first started interrogating Abu Zubaydah, and over the FBI agent's vociferous objections, a CIA contractor stepped in to take over the interrogation. The FBI's standard, noncoercive techniques were jettisoned and Abu Zubaydah was stripped naked, subjected to "wallings," deprived of sleep, slapped, locked in boxes, and repeatedly waterboarded, according to the 2014 Senate Intelligence Committee report about the CIA prison program. After one waterboarding session Abu Zubaydah "became completely unresponsive, with bubbles rising through his open, full mouth," according to the report.

In the top-secret memoranda prepared by the White House's Office of Legal Counsel that authorized the coercive interrogation techniques on Abu Zubaydah, he was variously described as "one of the highest ranking members of al Qaeda;" either the number three or four in the terror group, and as one of the planners of 9/11.

In fact, within weeks of Zubaydah's capture, it became clear to at least some US officials that he was not "al Qaeda's chief of operations," as he had been publicly described by President Bush on June 6, 2002, but rather someone who was a logistician for militants in Pakistan on their way to training camps in Afghanistan.

Then-FBI Special Agent Daniel Coleman, a top al Qaeda expert at the bureau, explained to me that Abu Zubaydah was simply a "travel agent; he wasn't a member of the inner circle" who would know about future operations, although he did know many members of al Qaeda by virtue of his role as a "safe house keeper."

But believing that Abu Zubaydah was, in fact, a very big al Qaeda fish, White House lawyers authorized continuous sleep deprivation of up to 180 hours (one week), face slapping, extended nudity, dietary manipulation, confinement in cramped boxes, being slammed into a flexible wall, and waterboarding, according to the findings of the Senate Intelligence Committee report. Those techniques were supposed to induce "a state of learned helplessness" in the detainee, who would then supposedly be putty in his interrogator's hands, according to the Senate report.

When I was reporting "The Longest War," Soufan told me that he objected that Zubaydah was being subjected to "borderline torture." Soufan was pulled out on the orders of his FBI superiors, who did not want the bureau's agents to be involved in coercive interrogations. Abu Zubaydah was later "waterboarded" at least 83 times by the CIA, The New York Times reported in 2009, citing a Justice Department legal memorandum from 2005.

In the end, the waterboarding of Abu Zubaydah provided no specific leads on any plots, although clearly his role as an al Qaeda logistician did give him insights into the organization and its personnel. The CIA destroyed the videotapes of the coercive interrogations of Abu Zubaydah in 2005, according to the Senate report. It's not too far-fetched to assume that, had the tapes ever been made public, they would have been quite damaging to the agency.

CNN obtained another tranche of Abu Zubaydah's drawings, which are published here for the first time. They are the most comprehensive visualizations of the coercive techniques that he says that were used against him.

Pretrial hearings at Guantanamo are underway in the separate case against five defendants, including Khalid Sheikh Mohammed, for their alleged roles in the 9/11 attacks. The CIA's coercive interrogations at its secret prisons have been the subject of days of testimony at those hearings in Guantanamo, and defense attorneys have argued that any evidence gathered from detainees gained by coercive techniques is inadmissible.

The CIA declined to comment on the newly obtained drawings showing the alleged coercive interrogation techniques.