Washington Post
9/11 Report Says Agencies Received Credible Clues

The U.S. intelligence community received a surprising number of credible reports of a likely terrorist attack prior to Sept. 11, including some threats to domestic targets, according to a congressional report to be unveiled today.
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After reading and analyzing hundreds of thousands of pages of documents from the CIA, the National Security Agency, the Defense Intelligence Agency and other government agencies, "you start thinking: Did anyone really explain to the public how serious this stuff was? . . . Did the American people really realize the strength of the threat out there?"
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...while the committee staff found no information that revealed the exact date, time and place of the attack, the official said there were numerous credible reports of possible domestic attacks and suggested that some may have been played down because the intelligence agencies were too focused on threats to U.S. interests overseas.

An intelligence briefing two months before the Sept. 11 attack warned that Osama bin Laden would launch a spectacular terrorist attack against U.S. or Israeli interests, congressional investigators said Wednesday.

The briefing, for senior government officials, was part of "a modest, but relatively steady stream of intelligence information indicating the possibility of terrorist attacks inside the United States," said the 30-page statement by Eleanor Hill, staff director for the House and Senate intelligence inquiry into the Sept. 11 attacks.

But Hill said the credibility of the sources was sometimes questionable and no specific details about the attacks were available.

"They generally did not contain specific information as to where, when and how a terrorist attack might occur and generally are not corroborated by further information," her statement said.

United States intelligence officials focused so much attention on the potential for attacks by Al Qaeda overseas that they underestimated reports before last Sept. 11 warning of a domestic attack, the joint Congressional committee investigating the World Trade Center and Pentagon attacks has found.

The committee has also determined that there were intelligence reports warning that Al Qaeda hoped to use aircraft as weapons against the United States, and the panel plans to raise questions about whether those reports should have been taken more seriously prior to Sept. 11, a Congressional official close to the committee said today.
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American intelligence officials have said that during the spring and summer of 2001, they picked up disturbing reports showing that Al Qaeda was planning a major attack. But the most specific reports suggested that the strike would come overseas.

That fit with Qaeda's earlier pattern of behavior. Prior to Sept. 11, Al Qaeda had repeatedly attacked American targets, but almost all of those operations had been abroad. The only operation known to be aimed at a domestic target was a plot to bomb Los Angeles International Airport, which was broken up before it could be carried out.