Anonymous wrote:What alternatives exist if you want to work in national security or defense?
Answering the second part of your query: there's the Department of Defense (War), of course. Treasury does some amazing things with their Terrorism & Financial Intelligence undersecretariat (money laundering, economic sanctions ...). Commerce's Bureau of Industry and Security prevents the export of sensitive intelligence (though I've heard from some that it's not in great shape right now). And there's the intel community.
You might consider joining the National Guard--military experience can be very useful in breaking into the intel world.