The best way for us to protect ourselves from those kinds of attacks is to stop f*cking with other peoples' countries. The more we do it, the more we make ourselves vulnerable to attack. There is no way for any imperialist power, no matter how well armed, and no matter how many people it tortures, kills, or maims, to completely protect itself from people who don't like imperialist bullies (and those are the kind of people who have made those kinds of low tech attacks against us). So the best way to protect ourselves from those people is to simply stop being an imperialist bully.

Think about it this way... possibly an interrogator might be able to find out where the ticking suitcase nuke is planted using torture. But only if they have someone in their custody who has that information. If they don't, it doesn't matter how many people they torture, they're not going to get the information. So the better way to guarantee our national safety is to simply not create so many reasons for people to hate us.