Philosophical Abstract: Let's say there are 500,000 Syrian Refugees wanting to come into the US in 2018. For every 100,000 Syrian refugees that you take into the United States, 2 US citizens will be killed in terrorist attacks. So assuming you take all 500,000 there will be 10 US citizens killed in terrorist attacks as a result.
On the other hand, for every 100,000 Syrian refugees left in Syria, 1,000 will be killed in war or die of malnutrition. Thus if you take no refugees, 5,000 Syrians will die as opposed to the 10 US citizens that would die if you took all of them in.
Not considering other cultural or economic aspects what do you do? Me personally, I'm leaving those mofos out to dry. Cuz fuck that shit, I aint tryina get killed. Aint my fault if dudes in the middle east keep icing each other.