There is a war between civilizaions. Let me ask you this question: Why does the US allow travel or immigration from any moslem country?
Because nobody in the establishment has been decapitated, burned, stabbed or run over yet. As well as an unholy alliance between the international left and Islamists bent on destroying Western Civ.
For one thing we have been admitting people who helped our troops in Iraq and Afghanistan as translators who are now in great danger at home. Another is that over the years many have emigrated to US as their countries collapsed into warfare or revolution. Iran is one example. I understand there are Iranian doctors working in our hospitals because our med schools are not turning out enough doctors.