I don’t mean to be alarmist, but I believe there is little anyone can do to prevent someone with money from buying a nuke and motoring (or sailing) it into a harbor in any coastal city in the world. I do not believe that more interations of the Patriot Act or more numerous and strict inspections of containers or more invasions of other countries would lessen the chances of this happening by any worthwhile degree. In this respect, I believe more money and power to Homeland Security would not help.
Frankly, I don’t know what would help other than being a country that people did not want to target. I don’t think this is possible, either, at least in the near term, and I don’t know what that would look like, anyway. I sure as hell don’t want the US to turn into a country no one gives a crap about, like Equador or something.
The Islamofacists have been working towards establishing a Muslim califate since the 1920s after the fall of the Ottoman califate, and will use any means neccessary to that end.
But since you think there is nothing we can do to stop it, I guess you may as well start studying the Koran and learn to speak Arabic to make for a warm welcome for them when they get here.