The manual introduced the concept of "acoustic shadowing" – using the echoes between buildings to mask movement. It included decibel tables for suppressed weapons vs. background urban noise (e.g., a subway train passing at 30 mph generates 95 dB, acceptable for M4 with suppressor).
While the original FOUO text is not public, academic papers and later training circulars (e.g., TC 90-1, 2008) cite specific chapters. A likely outline:
The term "Advanced" in the title is key. This was not a primer on basic room clearing (which is taught in basic training); it was designed for 12-man Operational Detachment Alpha (ODA) teams operating independently or with partner forces. The manual introduced the concept of "acoustic shadowing"
Key concepts covered in the manual included:
In the annals of modern military doctrine, few documents have carried the mystique of FM 31-28 (FOUO), titled Special Forces Advanced Urban Combat, effective 1 December 1999. Unlike its predecessor, the conventional FM 90-10 (Military Operations on Urbanized Terrain), this manual was not for line infantry or mechanized battalions. It was written specifically for the green berets of the U.S. Army Special Forces (SF), the “quiet professionals” who operate in small teams behind enemy lines. Efforts via the Freedom of Information Act (FOIA)
The identifier "25" likely refers to a specific paragraph, annex, or figure number within the document — perhaps detailing a 25-point urban breaching checklist, a 25-meter engagement drill, or Annex 25 covering underground tunnel networks. While the physical “FOUO” (For Official Use Only) stamped copies from 1999 have largely been recalled or destroyed, their doctrinal DNA survives in today’s urban warfare training at the SWCS (Special Warfare Center and School).
This article reconstructs the historical backdrop, core tactical innovations, and lasting legacy of FM 31-28, a manual that turned the claustrophobic chaos of city fighting into a systematic art form for 12-man detachments. known excised portions include:
Conventional manuals (FM 90-10-1) focused on battalion-and-brigade level combined arms: tanks, artillery, and engineers clearing block by block. That was useless for a 12-man Operational Detachment Alpha (ODA). On the other hand, traditional SF manuals focused on jungle or rural guerrilla operations. FM 31-28 was created to fill this void.
Surprisingly, FM 31-28 contained a section on commercial off-the-shelf (COTS) radio-controlled aircraft being weaponized by enemy forces. This was prophetic for 2020s drone warfare. Recommendation 25 in that chapter: use a 25-foot length of monofilament fishing line suspended between two buildings to entangle low-flying drones.
Efforts via the Freedom of Information Act (FOIA) for FM 31-28 (1999) have yielded mostly redacted responses. However, known excised portions include: