The death toll from the truck attack on a Christmas market in Berlin stands at twelve at this writing. ISIS has claimed responsibility for the slaughter.

New Year's Eve last year ushered the the old year out with attacks on women in Cologne and other European cities by men from the Middle East and North Africa. The press tried to ignore or downplay these attacks.

In the wake of these assaults on women, my colleague Carrie Lukas asked in the New Boston Post whether "immigration without assimilation" puts women at risk. Of course, the Christmas market attack reminds us that it puts everybody at risk.

The Wall Street Journal comments this morning:

The slap to Germany is particularly acute since Chancellor Merkel has worked so strenuously for a year and a half to convince her countrymen that welcoming migrants from the Middle East is an essential German value. She has done so even as German security officials warned that ISIS has slipped its operatives into Europe amid the hundreds of thousands of genuine refugees, and as some of those newly arrived migrants have been implicated in terror attacks, including July’s train incident.

Whether the attacker turns out to have arrived recently or to be a long-term resident who became radicalized in Germany, the proliferation of new threats is straining German security services. It’s almost inevitable that terrorists will slip through the cracks.

The result in this instance is a tragedy for the victims and their families, and also a warning to Mrs. Merkel. She helped create that overwhelming influx of migrants when she threw open Germany’s doors to them last year. Her “we can do it” mantra in the face of the migrant crisis will quickly become a “no we won’t” from voters if the government can’t show it’s able to provide basic security.

Questions of policing and surveillance are especially fraught in Germany in light of its 20th-century history. But terrorists will exploit any loophole they can find. Witness the Journal’s report that a 12-year-old German-Iraqi boy allegedly was recruited to attempt a bombing of another German Christmas market this month, and a 16-year-old girl was ordered by ISIS operatives to attempt an attack on police, in part because German law forbids surveillance of minors.

The modern West has a generous impulse to welcome strangers from different cultures, but it must be tempered with concerns for safety and assimilation: nobody has a right to live in a foreign nation, and a nation's leaders have an obligation to put the safety of its citizens and the values of their society first.