In the aftermath of 9/11 everyone, from elected officials and national security experts to ordinary citizens had one question: how could this happen to a nation with such an enormous and expensive military and intelligence architecture? The question was so ubiquitous that (in spite of some foot dragging by the Bush Administration) it eventually led to the creation of a high-level commission charged with seeking answers. Two and a half years after the attacks, in the summer of 2004, the Commission finished its work and released its report. The overriding conclusion was that the government’s principal failure in 9/11 was a failure to “connect the dots.” [1] What that meant was that pieces of the puzzle were to be found in many corners of the U.S. government but that no one connected the dots well enough or in a timely enough manner to predict with sufficient accuracy the attack that came.
9/11 and the reinvention of the US intelligence community (brookings.edu)