German police arrest three people, including a Tajik, linked to an alleged attack plot targeting the cathedral in Cologne on New Year's Eve. The suspects are believed to be connected to Islamic State-Khorasan (IS-K). Security measures have been increased in Cologne, with sniffer dogs searching for explosives in the underground parking of the cathedral. Around 1,000 police officers have been deployed to protect the cathedral and the population. Germany has been on high alert for possible Islamist attacks, with a previous attack carried out by an IS supporter in 2016.