The terrible writing and design of spook memos and Powerpoint slides have come to the fore since June 2013. However, that doesn't mean that there's not some pretty good style guides available for America's brave spooks. USA USA USA.
Bruce Schneier writes, "National Security Counselors law firm has obtained a copy of the CIA Directorate of Intelligence Style Manual, Eighth Edition, 2011. It is entitled Style Manual & Writers Guide for Intelligence Publications. There's also the NSA SIGINT Style Guide."