Honestly, you probably could get away with a Security+ for a while (if your already in a govt security position) because the 8570.01M indicates the need for a Security+ at the very least at IAM 1.

But if your position actually requires you to take an IAM roles at the Field Operating Agency enlcave systems or some other MAJCOM equivalent level than you should go for the CISSP. The DoD is talking about requiring an **Information System Security Engineering Professional certification, ISSEP (a certification that actually requires the CISSP to even take the test) for enclave systems.

This table is taken straight from the DoD 8570.01M:

from tao security

More on the 8570:
http://iase.disa.mil/eta/index.html#8570training

**Notes: The 8570 FAQ mentions that “Future updates to the Manual will incorporate specialized elements of the IA workforce. Chapters on System Architecture and Engineering and Computer Network Defense Service Providers have been drafted and are currently entering the formal DoD staffing process.” I haven’t been able to find the new 8570 Draft that refers to ISSEP, ISSAP (specialized CISSP) but I’ve been seeing it in slides and at briefing for about a year now.

Here is what is being proposed. This would actually affect me (I may have to get an ISSEP or ISSAP). Security+ will not cut it if this passes in the next DoD 8570 Draft.

Chapter 10: Information Systems Security Architects/Engineers
Level IASAE I IASAE II IASAE III
Certs CISSP CISSP ISSEP
ISSAP
Chapter 11: CND Service Providers
Role CND Analyst CND
Infrastructure
Support CND Incident Responder CND
Auditor CND SP Manager
Certs GCIA MCSA Security
SSCP GCIH
CSIH CISA
GSNA CISSP-SSMP
CISM

Ref: www.disa.mil/conferences/2007/briefings/iatool_training.ppt (slide 19 from DISA Conference)