Police in the German city of Cologne and Austrian capital Vienna have stepped up security measures following indications of possible attacks during the Christmas holidays. Security authorities said on Saturday they had received information about a possible attack plan by an Islamist group on Cologne Cathedral and a church in Vienna. The Austrian domestic intelligence service detained four people in an investigation into an Islamist network, according to the Interior Ministry on Sunday, Christmas Eve. The Directorate for State Security and Intelligence at the Austrian Interior Ministry said int...