Pre-Sept. 11 Warnings Were Unheeded

Feb. 18 -- The terrorist attacks of Sept. 11, the worst in U.S. history, came as a complete surprise to U.S. law enforcement and intelligence agencies.

There were no alerts, no increased security, no warnings. An ABCNEWS investigation of the failure of intelligence on Sept. 11 has found a trail of missed signals, missed opportunities, and warnings ignored.

There were warnings about the possibility of an airborne terrorist attack on U.S. targets as early as 1994, when terrorism expert Marvin Cetron underlined the threat in a report to the Pentagon.

"We saw Osama bin Laden. We spelled it out and we said the United States was very vulnerable," Cetron told ABCNEWS. "You could make a left turn at the Washington Monument and take out the White House. And you could make a right turn and take out the Pentagon."

Cetron said he warned the Pentagon that two events earlier that year — the crash-landing of a small airplane at the White House by an apparently unstable man, and French authorities' storming of a hijacked airliner that Algerian terrorists had planned to fly into the Eiffel Tower — made an airborne terrorist attack on the United States a very real possibility. "We knew that was going happen and we were scared," he told ABCNEWS.

But Cetron said Pentagon officials told him to delete the warning from the report. "I said, 'It's unclassified, everything is available,' and they said, 'We don't want it released because you can't handle a crisis before it becomes a crisis, and no one is going to believe it anyhow,' " Cetron said. Even with the warnings of an airborne attack deleted, the report was not released to the public.

Aversion to Risk

Four years later, in 1998, U.S. authorities faced a terrorist crisis with the bombings of the U.S. embassies in Kenya and Tanzania. The United States accused bin Laden of involvement, and Congress and the Clinton administration commissioned two new reports on terrorism.

Both of the reports rang alarm bells, but little was done.