Washington DC - The CIA released more than 70 presidential intelligence briefs related to Al-Qaeda and its leader Osama bin Laden on Friday, the 25th anniversary of the September 11, 2001 attacks.
The release provides "unprecedented transparency on America's most sensitive intelligence publication from the years before and the day after one of the darkest moments in our history," the CIA said in a statement.
"The products trace the story of CIA analysts' evolving understanding of Al-Qaeda and efforts to highlight and warn of Osama bin Laden's attack plotting despite sparse, vague, and imperfect information," it said.
A September 10, 1998 brief – parts of which were redacted – said that Al-Qaeda "may fly an explosive-packed airplane into a US city."
Another dated December 4, 1998, which also contained redactions, said bin Laden "and his allies are preparing for attacks in the US, including an aircraft hijacking."
The briefs cover a period starting during Bill Clinton's presidency and continue into that of George W. Bush, who was in office when 19 Al-Qaeda operatives hijacked four airliners on September 11, 2001.
Two of the jets hit the World Trade Center's Twin Towers, causing the iconic skyscrapers to collapse.
A third struck the Pentagon, while a fourth – believed to have been aiming for Congress or the White House – crashed into a field in Pennsylvania after passengers fought back.
The US invaded Afghanistan and later Iraq as part of the so-called "War on Terror" after 9/11 – long-running wars that left tens of thousands of people dead.