The holidays are starting. But good cheer is in short supply. Christmas markets in Europe have tightened security, following U.S. travel warnings to its citizens over an increased threat of terror attacks at holiday venues. The organizer of one Berlin Christmas market says everyone's preparing. (SOUNDBITE) (German) GENDARMENMARKT CHRISTMAS MARKET MANAGER, GUNDA KNIEP, SAYING: "Danger can never be ruled out but my hope is that our square is not the focus in Berlin. At least that's my hope." And for many shoppers and vendors in Berlin, defiance of the threat sends an important message.. (SOUNDBITE) (German) CHRISTMAS MARKET VENDOR, BEA LOEWWEINLEIN, SAYING: "If we let ourselves be limited in our movements that's exactly what they want, that no one leaves home anymore." In France, the police presence seems especially pronounced. After the deadly 2015 Paris attacks, they're doing what they can to make sure this holiday season passes without violence. Website: http://timesofoman.com Facebook: http://facebook.com/timesofoman Twitter: http://twitter.com/timesofoman