Twenty years after the 9/11 attacks, U.S. intelligence documents reveal 229 “rehabbed” former Gitmo detainees have returned to terrorism and killing Americans — and an alarming 66% of them have not been recaptured and are still at large.

Meanwhile, President Biden is quietly freeing more of these terrorist suspects from the Guantanamo Bay prison, all to fulfill his old boss’ pledge to permanently close the facility in Cuba.

Shortly after taking office, Biden reversed President Trump’s executive order to keep Gitmo open and is lining up inmates to transfer out of the prison with the goal of emptying it and shuttering it — even though the remaining prisoners have long been classified by military intelligence as the worst of the worst and too dangerous to release.

Last month, the president freed his first prisoner — accused terrorist Abdul Latif Nasser — leaving the number of remaining detainees at 39. Ten others have been cleared for release, including some of Osama bin Laden’s bodyguards and 9/11 mastermind Khalid Sheikh Mohammed’s safehouse operator, according to Gitmo parole board documents.

Still other detainees have appealed to the Biden administration through their pro-bono defense lawyers to ensure their release, despite the risk of them returning to militant activities. The suspected 20th hijacker, Mohammad al-Qahtani, and a dozen other inmates are slated for parole hearings this year, documents reveal.

Biden is clearing out the cells despite being fully briefed by his intelligence agencies that one in three released detainees have gone back to fighting against America — and some have actually managed to kill more Americans.

“Based on trends identified during the past 17 years, we assess that some detainees currently at GTMO will seek to reengage in terrorist or insurgent activities after they are transferred,” a recent US intelligence report warned.

According to the December 2020 declassified report by the Office of National Intelligence, a total of 229 of the 729 detainees released from Gitmo have reengaged in terrorist activities, including conducting and planning attacks and recruiting and funding terrorists. That’s a recidivism rate of 31%. (The share would be even higher if US intelligence included engagement in anti-US statements or propaganda in its definition of “terrorist activities.”)

Some of the repeat offenders have since died or been recaptured, but 151 — or 66% —  are still at large, the document reveals.

And some have American blood on their hands. At least 12 released detainees have launched attacks on US forces in Afghanistan and killed about a half-dozen American soldiers and civilians. The exact figure remains classified.

In fact, most of the former detainees found reengaging in terrorist activities are Afghans, which raises security alarms given the Taliban’s sacking of the US-backed government in Kabul and the flood of largely unvetted Afghan refugees being resettled in US cities. More than 200 Afghan prisoners have been repatriated from Gitmo.

One notorious Gitmo recidivist, Abdullah Gulam Rasoul, became the Taliban’s operations commander in southern Afghanistan soon after his 2007 release from the prison. He was blamed for masterminding a surge in roadside attacks against American troops and organizing assaults on US aircraft in Afghanistan.

The Taliban has relied on former detainees to fill other key leadership roles as well, including the “Taliban Five” who were released by President Obama in 2014 over Pentagon objections and are now top dogs in the revamped enemy group. As the Post first reported Monday, at least one of the freed Taliban commanders engaged in talks with Biden diplomats to secure the precipitous withdrawal of US troops from Afghanistan. In addition, Mullah Zakir was sent from Gitmo to Afghanistan in 2007, where he became one of the Taliban’s top military chiefs.