"We're concerned about it," he said, according to WCBS/Channel 2. "We of course are concerned particularly because [Osama] bin Laden spoke about it twice in the notes that were recovered [during the May raid in which he was killed]."
The FBI and Department of Homeland Security issued a nationwide law enforcement bulletin Friday, just days before the 10th Anniversary of 9/11, warning of the threat.
"Al Qaeda and its affiliates have maintained an interest in obtaining aviation training, particularly on small aircraft, and in recruiting Western individuals for training in Europe or the United States, although we do not have current, credible information or intelligence of an imminent attack being planned," according to the Associated Press, which obtained the memo.
Kelly said there was no specific information about a plot, but security was stepped up as a precaution, WCBS said.