Well that's pretty simple, but not neccesarily a all out ban but a nice background check on who's who could do a little better job. The open border policy and the pushing of multiculturalism has made it a lot, a lot harder to do so. Also, people should arm themselves, you can never be too safe in this time.
Here is what the President-Elect has to say.
http://time.com/4611229/donald-trump-berlin-attack/
President-elect Donald Trump on Wednesday called the recent attacks in Germany and Turkey “terrible” and suggested that he does not intend to reevaluate his plans to ban Muslims from immigrating to the United States, boasting that he had been “proven to be right.”
“You know my plans. All along, I’ve been proven to be right. 100% correct. What’s happening is disgraceful,” Trump told reporters Wednesday when asked whether the recent violence has influenced his proposed Muslim ban.
Trump described the attack at a Berlin Christmas market as an “attack on humanity.”
“That’s what it is: an attack on humanity,” he said. “And it’s got to be stopped.”
Trump said he had not spoken with President Obama since the attacks.
“Innocent civilians were murdered in the streets as they prepared to celebrate the Christmas holiday,” Trump said in an initial statement about the attack on Monday. “ISIS and other Islamist terrorists continually slaughter Christians in their communities and places of worship as part of their global jihad.”