The head of PET, Denmark’s secret service agency, said the agency and the government are taking measures to crack down on Danes who travel to Syria to fight with the rebels, who pose “one of the most serious security risks to the Danish society at the moment.” PET estimates that at least 65 Danes have fought in the conflict; five are known to have been killed in Syria. Many of the Danish fighters are said to have joined the al Qaeda-linked Al Nusrah Front.