There are great people all over the US Government doing their level best to keep us protected. TSA (Which is part of DHS as you know), the rest of DHS, DoD, the intel community. The problem is we have to be right 100% of the time. If we miss just one time the bad guys score a win… and because of how classified all the good work of these agencies and the men and women in them, most people don't even know about the literally thousands of attacks averted ever year. If they did, they'd be screaming for that wall. The ironic part is, when the terrorists do get through it'll be the very people who are protesting the wall who will blame President Trump and every agency in the Government for not doing enough.