A warning sent to the White House before the 9/11 attacks has been declassified by the CIA. The warning, part of a presidential intelligence report, mentioned a group linked to Osama bin Laden that could crash a plane into a US city. This report was delivered on September 10, 1998, to then President Bill Clinton.

The warning did not specify the use of explosives, but rather the potential for a plane to be used in an attack. The actual 9/11 attacks involved four planes, with targets including the World Trade Center and the Pentagon.

More information is available from the source, including over 100 pages of declassified daily presidential intelligence reports.