Your fear emphasizes the lack of one of those most important American values. Courage. Also, I never said anything about this being about "how many Americans are killed by terrorists." 

Have you ever worked in any program that deals with the assimilation of refugees? I have. In 2009, assisted in developing and running a self-funded (no tax dollars or UN money), neighborhood based cultural exchange program for Rohingya Muslim  and Karen refugees from Burma and Muslim Iranian refugees. They learned English and I ate great food. Those refugees and immigrants now own restaurants and run their own shops, hell they even eat apple pie. Best part, they're my neighbors. 

Assimilation happens here and now because normal Americans, with full-time jobs and families, decide to be there to support the process.