A German woman was hacked/stabbed to death by a Syrian migrant near Stuttgart Germany this after an argument. Two others injured
http://www.bbc.com/news/world-europe-36879196
http://www.bbc.com/news/world-europe-36879196
And our country has said it will allow 65,000 Syrian migrants into the US in the next fiscal year.
The difference between those immigrants who may wind up coming to the US and the guy in Germany is that 'yours' will likely have been strenuously vetted and chosen from camps by people who are experts at the job as opposed to the flood of unknown immigrants who filled the roads of the EU.
I really don't think there's much we can do about it, we don't want to ban these folks and it's probably impossible to efficiently vet them all. It's a chance we all take. Americans should be given a credit or rebate for buying guns and ammo these days. When/if the $hit hits the fan, at least we won't all be standing there with a dumb look on our face while these terrorists slaughter the innocent like they do in these other countries. The authorities and helpless citizens both will rely on those who can act to protect if needed, although they'll deny that fact until things get really ugly. Hopefully that never happens.