What did US intelligence know before the 9/11 attacks?

What the report says

The CIA has declassified a large set of presidential daily briefs that shed light on what US leaders were told about Osama bin Laden and al-Qaeda before the September 11 attacks. Al Jazeera reports that the release, announced 25 years after 9/11, is the agency’s largest publication of these highly classified intelligence summaries and covers material from February 1998 through September 12, 2001.

According to the article, the documents show intelligence analysts following bin Laden’s movements, financing, ties inside and outside the United States, and his interest in unconventional weapons. Some briefs included specific warnings that al-Qaeda-linked extremists might use aircraft in an attack, while others described plans involving hijacking training and efforts to obtain chemical, biological or radiological materials. The files also show that officials repeatedly warned presidents Bill Clinton and George W. Bush about the threat, with the language becoming sharper in 2001.

Al Jazeera says the release does not prove that the US government knew the exact details of the 9/11 plot or that officials had prior knowledge of the attacks. Instead, it adds more primary-source evidence to the long-standing view that intelligence agencies had gathered many warning signs but did not assemble them into a complete picture in time. Some of the newly released briefs had been seen before, including the well-known August 6, 2001 memo warning that bin Laden was determined to strike in the US.