Best Government Agency after Marines?

I would like to get a job in something like the CIA, NSA, DOD, or fletchrc told me about the DOS. I will have a Bachelors degree in Political Science and I will be above a 2nd Lt. What can you recommend to me? I am very interested in International affairs and national security. Thanks and God bless the families and friends of those that lost their lives 9 years ago today.