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

The CIA has published a set of presidential daily briefs that illuminate what intelligence reached the White House about Osama bin Laden and al-Qaeda in the years before the Sept. 11, 2001 attacks. The collection — the agency’s largest-ever release of presidential briefs — spans 71 documents and 101 pages, running from February 1998 through the day after the attacks on New York and Washington. CIA Director John Ratcliffe described the release as “an act of exceptional transparency.” Many pages remain redacted to protect sources.

Taken together, the papers show analysts were following bin Laden’s movements, funding streams, and support networks at home and abroad. They flag his interest in chemical, biological and radiological weapons and, by mid-1999, report experiments aimed at increasing explosive energy consistent with concerns about so-called “dirty bombs.” The briefs also document the Taliban’s unwillingness to surrender bin Laden, noting in 1998 that he was effectively treated as a guest and that past assistance during the Soviet occupation made the Taliban reluctant to monitor or control him.

Several memos contained strikingly specific warnings about potential attack methods. A September 1998 briefing recorded a stated preference by bin Laden to strike Washington and noted that the group behind that summer’s East Africa embassy bombings “may fly an explosive-packed airplane into a US city.” A December 4, 1998 brief referenced operatives who had evaded security checks during a trial run at a New York airport and said some network members had received hijack training. One of the better-known documents in the release, previously declassified, is the Aug. 6, 2001 brief titled “Bin Ladin Determined To Strike in US.”

The newly posted files do not supply detailed new evidence about how the Sept. 11 plot was planned or identify the precise time, place or method of the attacks. Instead, they provide a paper trail of mounting warnings that intelligence agencies had accumulated over several years. The release reinforces earlier conclusions — including those of the 9/11 Commission — that agencies held many fragments of relevant intelligence but did not assemble them into a clear, actionable picture before the attacks. The documents contain no evidence to support claims that the US government had prior knowledge of or involvement in the attacks.