FILE-In this Wednesday, Aug. 21, 2013 file photo, DeKalb County Police Chief Cedric L. Alexander listens to a question during a news conference in Tucker, Ga. Legions of police and federal agents will be protecting the stadium as Atlanta hosts Super Bowl 53, but recent attacks in the U.S. and around the world underscore how terrorists are striking less-secure areas outside sports stadiums, arenas and airports, experts say. (AP Photo/John Bazemore, File)

FILE-In this Friday, Sep. 21, 2018, photo, Mercedes-Benz Stadium is seen in this aerial photo in Atlanta. The stadium will be the site of Super Bowl LIII on Sunday, Feb. 3, 2019. Legions of police and federal agents will be protecting the stadium as Atlanta hosts Super Bowl 53, but recent attacks in the U.S. and around the world underscore how terrorists are striking less-secure areas outside sports stadiums, arenas and airports, experts say.(AP Photo/Danny Karnik, File)

FILE-In this Thursday, Jan. 4, 2018 file photo, Atlanta Police Chief Erika Shields attends a press conference in Atlanta. Legions of police and federal agents will be protecting the stadium as Atlanta hosts Super Bowl 53, but recent attacks in the U.S. and around the world underscore how terrorists are striking less-secure areas outside sports stadiums, arenas and airports, experts say. (AP Photo/David Goldman, File)