I agree with your main premise but don't see how we can ignore them and hope they never develop the capability to hit us without actually stepping foot on our land.
They, like our own Left, will never cease their efforts, and recognition of that is key to being postured to protect our People.
That is a problem. That is why we have also to ban nuclear material being allowed in these countries and especially in Iran. However, at present, Europe is within missile range. We are not. If anything Europe should be very worried, but as usual, they are not.
Now we have problems with Canada and Mexico letting in anyone they want. This is a huge problem. But we can focus on tracking nuclear material and other surveillance means to do targeted strikes against cells that are working on nuclear devices (Iraels Mossad does this).
But a full scale war with these people and airstrikes is not going to do it. First of all it will not work. Secondly it will make the problem worse.
Containment is our best strategy at the moment. It is not perfect but it is better than going to war with almost 1/4 of the world’s population.