>... Had they been doing so pre 9/11 we might still have those two buildings and several thousand people.

But we didn't know they were here until it was too late," Bush said. "The authorization I gave the National Security Agency after Sept. 11 helped address that problem in a way that is fully consistent with my constitutional responsibilities and authorities."

Some current and former high-ranking U.S. counterterrorism officials, however, say that the still-classified details of the case undermine the president's rationale for the recently disclosed NSA domestic spying program, not support it.

What Bush didn't disclose is that while living together in San Diego, al-Hazmi and al-Midhar were communicating with a phone number originating from a suspected al-Qaida safe house in Yemen. The site had already been linked directly to the al-Qaida bombings of two U.S. embassies in Africa in 1998 and to the 2000 bombing of the USS Cole in Yemen, according to several current and former U.S. counterterrorism officials familiar with the case.

Because of those links, the safe house was one of the "hottest" surveillance targets monitored by the NSA before the Sept. 11 attacks and had been for at least several years, the officials said.

Authorities also had known for years that the phone number at the safe house, which was used to call al-Midhar in the United States on at least six occasions, was traced to al-Midhar's father-in-law, and say they believed at the time that two other sons-in-law had already martyred themselves in suicide terrorist attacks. Such information, the officials said, should have set off alarm bells at the highest levels of U.S. government before Sept. 11.

But no additional surveillance authority was needed, these officials said; under existing and well-established federal law, the NSA was already listening in on that number and could have tracked calls made into the United States by obtaining a FISA warrant, under the Foreign Intelligence Surveillance Act.

Then the agency could have - and should have - alerted the FBI, which could have then used the information to locate the future hijackers in San Diego and monitor their phone calls, e-mail and other activities to see what they were up to, according to the officials.

Instead, the NSA never disclosed the existence of the calls, much less what the parties discussed, until well after the Sept. 11 attacks, according to these officials and U.S. documents.

"The NSA was well aware of how hot the number was ... and how it was a logistical hub for al-Qaida, and it was also calling the numbers in America half a dozen times after the Cole and before Sept 11," said one senior U.S. counterterrorism official familiar with the case.

Like other current and former officials, the senior counter-terrorism official would only speak on the condition of anonymity because of the classified nature of the intercepts and the controversy engulfing the secret program since its disclosure last week.

The official said he could not comment on what kind of information was being produced through surveillance of the Yemen safe house, except to say that the NSA, the FBI and other U.S. authorities had reaped a bonanza of intelligence from it over the years.

Some current and senior officials, including former Bush administration counterterrorism chief Richard A. Clarke, said the NSA could have listened in on such conversations. Clarke said he even received transcripts from the NSA of such conversations, but that comments by persons in the United States were redacted. Even so, Clarke and others said, the law allowed enough information to be "handed off" to domestic authorities to allow them to pick up the domestic trail.