1976, Michael T. Chase, “All-Source Intelligence”, in Military Review: Professional Journal of the U.S. Army, volume LVI, number 7, page 45:
While this cannot be done in all cases, no commander should accept the notion that whole blocks of intelligence are permanently behind a special “green door” until his intelligence officer has carefully examined the regulations.
1995, Douglas H. Dearth, R. Thomas Goodden, Strategic Intelligence: Theory and Application, second edition, page 66-67:
The so-called “green door”, behind which intelligence is alleged to hoard its secrets has always been, and forever will be, a problem. […] Arranging for dissemination of a specific, known product is relatively easy—it’s the products you don’t know about that the green door hides.
2005, editors Burton Gerber, Jennifer E. Sims, Transforming U.S. Intelligence, page 151:
The NSA is the opposite of the NGA in that the controlled serendipity of its collection-management processes is hidden not only from those beyond the “green door” but from many intelligence community insiders as well.
2012, Gaillard R. Peck, Jr, America’s Secret MiG Squadron: The Red Eagles of Project CONSTANT PEG:
This information on how the enemy conducted fighter operations came to the Aggressors from many sources behind the “green door” of the US intelligence gathering and interpreting community.
