The CIA has declassified dozens of presidential intelligence briefings revealing that US officials were warned years before the September 11 attacks that Osama bin Laden and his Al-Qaeda network were considering strikes on American soil involving hijacked or explosive-packed aircraft, while also pursuing biological, chemical, and nuclear weapons.

The agency released 71 President’s Daily Brief (PDB) products on Friday to mark the 25th anniversary of 9/11. The collection, totaling more than 100 pages, is the largest release of CIA presidential intelligence related to the attacks and covers assessments dating from 1998 through the immediate aftermath of September 11, 2001.

Among the most striking documents is a September 1998 memorandum on Bin Laden’s intentions. Intelligence indicated that his “preferred option” was to strike the US “on its own soil in Washington,” the CIA wrote, warning that his network “may fly an explosive-packed airplane into a US city.”

Three months later, another briefing warned that Bin Laden and his allies were preparing attacks in the US, including a plan to hijack an American airliner during the holiday season.

The newly released material also shows persistent concern about unconventional weapons. A February 1998 assessment claimed Bin Laden and other extremists sought to procure unspecified chemical, biological, and nuclear substances. By May 1999, the CIA assessed that Bin Laden was pursuing “a variety of options” for developing these types of weapons. A subsequent briefing in June said trainees at an Afghan camp produced and tested “dozens of toxic chemicals and biological toxins,” and that operatives experimented with adding radioactive material to explosives.

The best-known warning came on August 6, 2001, when then-President George W. Bush received a briefing titled ‘Bin Ladin Determined To Strike in US’. It said Bin Laden had wanted to attack the US for years, cited suspicious activity consistent with preparations for hijackings, and noted that the FBI was conducting around 70 investigations into possible Al-Qaeda-linked activity in the country.

By the summer of 2001, then-CIA Director George Tenet later recalled, the intelligence system was “blinking red.”

The 9/11 Commission found that many officials knew “something terrible was planned,” but failures in intelligence sharing, policy, and preparedness prevented the scattered warnings from being turned into action.

Bin Laden rose to prominence during the Soviet war in Afghanistan, when Washington poured billions of dollars into arming anti-Soviet mujahideen through Pakistan. US officials have denied directly funding Bin Laden, but the American-backed war helped create the militant infrastructure and environment from which Al-Qaeda later emerged.

The deadliest terrorist attack in US history, which killed 2,977 people, prompted Washington to launch the War on Terror, invading Afghanistan within weeks and Iraq less than two years later. At home, the PATRIOT Act vastly expanded the government’s powers to spy on its own citizens.