Dilbert's Scott Adams gives you something scary to think about with national security.
As far as I can tell, homeland security seems effective under President Obama, at least in terms of preventing Belgium-sized attacks. But we have a growing risk from terrorists disguised as immigrants from the middle east. There’s no way to assess that risk because we don’t know how well the vetting process in this country works. But if we assume the people doing the vetting are no more competent than your coworkers, reach your own conclusions about that risk.