Here is a piece I missed from last Friday at Conservative Review written by one of the sharpest policy minds in the blogosphere, Daniel Horowitz.
From ‘Chattanooga: The Effects of Our Suicidal Immigration Policy‘ (hat tip: Joanne):

After 9/11, when the bipartisan 9/11 Commission identified the obvious root cause of the attack as an immigration problem, we doubled down on stupidity. The U.S. has admitted roughly 1.6 million individuals from predominantly Muslim countries since 9/11 – twice the rate of immigration from that part of the world relative to the previous decade.

[….]

According to a new poll commissioned by the Center for Security Policy, 51% of Muslims in America believe “Muslims in America should have the choice of being governed according to sharia.” Twenty-nine percent agree that violence against those who insult Mohammad is acceptable and 25% agree that violence against America can be justified as part of Global Jihad. Among males under the age of 45 that number rises to 36%. Twenty-nine percent of males under 45 believe that violence against America is justified in order to make Sharia the law of the land. With an estimated 3 million Muslims in this country (projected to triple by 2050), that could mean there are hundreds of thousands of radicalized ones.

The more precipitously Muslim immigrants are admitted to this country, the less likely they will assimilate and the more likely they will cluster in cities and cultivate a climate of Jihad. The numbers speak for themselves. This is by no means the majority of Muslims, but 25% support for Jihad is an awful lot of security risks, especially among young males.

[….]

One of the most imminent threats to our country is the broken refugee system.

Continue reading here and see three things Horowitz says Congress must do to keep us safe.
I suggest a fourth!  In addition to holding up the Syrian resettlement, we need a moratorium on all immigration from countries that hate us and it isn’t simply to avoid more terror attacks, it is to stop the Hijra!  Hijra is the insidious Islamic Doctrine of immigration—Mohammed told his followers to go forth and spread Islam across the world and they are doing it!  That (for me) is the existential threat facing America.  It may take them decades to achieve their goal, but they work on the migration jihad every single day as we simply talk about terrorism in the short term.
By the way, I was glad to see that Horowitz has screen shots from the State Department data base I mention frequently.