Trotta said motorcades always present line-of-sight issues, and the inaugural parade is no exception.
"The exposure's there. The length of time is there. It's a parade. We're moving the White House in the middle of a parade," Trotta said.
There has been no specific intelligence pointing to a potential terrorist attack during the inauguration, said Joseph Persichini Jr., assistant FBI director in charge of the Washington Field Office.
"But we're always vigilant," he said, adding that visitors should help by watching for any suspicious activity.
Associated Press writer Nafeesa Syeed contributed to this report.