Germany's Christmas markets are world-renowned. But an attack in Berlin on Monday changed one from a scene of holiday cheer to one of death and destruction.
A truck rammed into crowds and stalls. Twelve people were killed, and 48 injured. And police scrambled to find the person responsible.
They arrested a Pakistani refugee, but released him through lack of evidence. Then they began to search for a Tunisian man whose ID was found in the truck.
The Islamic State of Iraq and the Levant group has claimed the attack, but its role remains unclear and unverified.
So what are the political and security ramifications from this latest atrocity?
Presenter: Sami Zeidan
John Duke Anthony, founding president of the National Council on US-Arab Relations
Raphael Bossong, research associate at the German Institute for International and Security Affairs
Imad Khchifati, a Syrian refugee who was granted asylum in Austria
Source: Al Jazeera News