The FBI agent who wrote a memo warning that terrorists were training at flight schools before the Sept. 11 attacks said concerns over racial profiling may have prevented officials from acting on his intelligence.

"If you look at the world prior to 9/11, we were prevented from doing certain things. We were victimized by our own restraints," Ken Williams (search) told The Arizona Republic in his first interview since writing his now-famous memo in July 2001.

Williams' findings were based on investigations of Arizona aviation students tied to Al Qaeda. At the time, he recommended the State Department coordinate with the FBI to provide information on flight students from Middle Eastern countries.

His memo was ignored by supervisors until after the attacks, but Williams said it was not a case of incompetence or malfeasance and he never blamed supervisors for the intelligence failure.

Even while writing his memo, Williams said, he never imagined that terrorists would fly a jumbo jet into a building. But on the morning of Sept. 11, 2001, Williams said he was galvanized by one thought: "Usama bin Laden . It couldn't be anyone else."

Williams said he is still following leads from his memo, but he refused to discuss specific findings.

Williams also said Americans have to reclaim the sense of unity they had three years ago to thwart another terrorist attack.

"They are going to try and hit us again," he said.