In a shock attack on Monday in Berlin, a truck crashed through a Christmas market, killing 12 people and injuring 48.
The attack highlights the difficulty of protecting 'soft targets'—areas with low-security and trafficked mainly by civilians, like cafes and movie theaters—said security expert and host of "The SCIF" podcast Juliette Kayyem.
"You can't fortify congregations of people against someone who is essentially hellbent on getting through them," she explained. "It's a challenge in Germany, it's a challenge in Europe right now."
Investigators are currently searching for a 24-year old Tunisian man suspected of being involved in the attacks. Depending on the identity of the attacker, Kayyem said, the attack could impact not only German Chancellor Angela Merkel's political future, but the future of Europe's refugee program.
"If it is a refugee-seeker, an asylum-seeker, it is very bad news for her," Kayyem said. "She's entering a campaign next year and we've got far right elements in Germany as we do in Europe."
"It's very bad news for her, and it's bad news for those who want to continue to keep our doors open to a limited number of refugees who go through a very rigorous process here," she continued.
To hear more from homeland security expert Juliette Kayyem, tune in to Boston Public Radio above.