9/11 Was 'Zero Day' in Intercepted Warning

June 19 -- The National Security Agency intercepted two messages the day before Sept. 11 where the participants referred to "zero day" and beginning of "the match," intelligence sources told ABCNEWS.

The agency, sources said, secretly intercepted and recorded two conversations in Arabic on Sept. 10. One said, "Tomorrow is zero day." Another intercepted message said, "The match begins tomorrow."

However, the information was not translated until after the attacks — on Sept. 12 — and, sources said, even if the messages had been translated sooner, it would not have been of much use because the messages were too vague and had no context, with no details of time, location or the nature of the event referred to.

The sources did not consider the information to be a smoking gun, and described it as the sort of chatter that is intercepted constantly, and is seldom of use.

However, earlier this month, one source told ABCNEWS the information National Security Agency officials received was the kind of thing that might have prompted an alert, if it had been known to other parts of the law enforcement and intelligence communities.

The NSA often has a lag in translating information, and was too overwhelmed with data to translate the two messages before the attacks, sources said.

Part of the problem is that the agency, which coordinates, directs, and engages in specialized activities to protect U.S. information systems and produce foreign intelligence information, gets millions of pieces of information, and does not have enough analysts to search through it all and interpret it. It often takes a couple of days to make translations.

Less Important Than Previous Revelations?

Officials do not feel that news of the interceptions is as important as other intelligence failures that have come to light.

Sources told ABCNEWS earlier this month that the CIA knew that two of the Sept. 11 hijackers met with al Qaeda operatives in Malaysia in January 2000 — more than 18 months before the attacks — but apparently did not convince the FBI to track them until less than three weeks before the attacks. Agents were searching for the two hijackers — Nawaf Alhazmi and Khalid Almihdhar — in New York on Sept. 10, the day the NSA intercepted its messages.