What is an EAM?

By Jeff Haverlah

 "EAM: Though generally referring to a category of urgent messages from commanders to deployed forces, EAM is often used as a short-hand expression for a specially coded nuclear attack directive."

    From "Strategic Command, Control, and Communication - Alternative Approaches For Modernization"; John J Hare, Richard H. Davison, and Peter Tarpgaars; Congressional Budget Office (CBO); October 1981; Page 44:

 "....Proper coding and formatting of EAMs is of crucial importance, since nuclear forces are prepared to execute any messages they receive that meet rigid specifications. In addition to specific instructions contained in an EAM, proper coding provides the means by which a commander expresses his authority to release nuclear weapons and an officer controlling those weapons verifies that authority."

     Ibid, Page 12:

“[In the December 94 issue of Monitoring Times] we talked about the U.S. military's Emergency Action Messages (EAM) broadcast. Here is an interesting explanation, taken from a U.S. Air Force manual, of what an EAM is.

 "Joint Chiefs of Staff Emergency Action Messages (EAMs) contain key instructions or information from high level authority and have predetermined formats (pro forma). Such messages are transmitted by various communications systems and normally carry FLASH precedence. They are vital messages of an extremely time-sensitive nature, and rapid processing is mandatory to obtain the fast reaction required by their content. Usage and handling procedures are of the highest classification and have been issued by the JCS only to those who have a need to know." (AFM-01-1-18, sub 3; amended 01 Jan 1990)."

     From the May 1995 Monitoring Times; Utility World column by Larry Van Horn; page 33; section titled "What are EAMs?":


From a shortwave utility hobbyist's standpoint what are they? Park your HF receiver (set to upper side band mode) on 15016.0 kHz, 13200.0 kHz, 11175.0 kHz (the most productive for day to day monitoring of the U.S. military on HF), 8992.0 kHz (ideal for monitoring during North American nights), 6739.0 kHz , 6712.0 kHz or 4724.0 kHz.

Eventually you'll hear ground stations of the USAF's HF-GCS (led by ANDREWS or OFFUTT or MCCLELLAN, identified in the clear since 1992) broadcast one or more Emergency Action Message, or EAM. You will hear a six-character alpha-numeric string (known as the "preamble") read phonetically, repeated three times. This will be followed by the same 6-character string either by itself (as the entire message), or concatenated with additional alpha-numeric characters to produce alpha-numeric strings that total 28 characters (the most common length; 30-characters prior to 01 Oct 2000; 26-characters prior to 01 Oct 1998), or 22 characters (20 character prior to 01 Oct 2000), or strings with character-counts that can extend into the hundreds of characters (with the available character set universe consisting of all 26-characters of the English alphabet plus the numerals two, three, four, five, six and seven; with extremely rare exceptions there are no zeros, ones, eights or nines heard in these strings).

[Eventually you might discover that this HF EAM activity is also heard on a group of HF frequencies that are known as the ZULU frequencies utilized by communication assets (both airborne and ground based) of the JCS and U.S. Strategic Command (see the "Military Lists Area" column in any recent WUN newsletter for the known frequencies) and on HF frequencies utilized by the U.S. Navy during apparent exercises. However, since FY 2000 the ZULU frequencies have become much less active with daily connectivity communications to the point of silence.]

The above activity is heard daily, 7 days a week, 365 days a year, year after year.

 A second group of coded messages heard on the GHFS (and the ones that produce the most comments from new listeners because of the "SKYKING do not answer" nature of the broadcasts) are the so-called FOXTROT broadcasts. These are heard only on the GHFS frequencies listed in the previous paragraph and take the form of the GHFS operator broadcasting a message that states "SKYKING, SKYKING. Do not answer. [3-element alpha-numeric group] [minutestamp] [time dependent two-character authenticator]" and repeated once.

These transmissions appear to be initiated by any of the GHFS ground stations except ASCENSION and HICKAM, with the initiating ground station prefacing the broadcast with a codeword that can consist of DECENT (or DESCENT), ENLIST, FAIRLY, EYESTRAIN (or sounds as), DEFROSTER, "ANY STATION" and maybe one more codeword recently reported. The codeword appears to determine which other GHFS ground stations are to "echo" the transmission. As an example, the DECENT transmission appears to apply only to CONUS stations while all the others appear to apply (with an occasional exception) to non-CONUS stations that fall outside an arc from Guam to Japan to Alaska to Greenland to the UK to the Azores.

These coded messages are said to be *only* for the positive control of ACC/AMC airborne forces detailed to the U.S. Strategic Command (USSTRATCOM). These messages appear to have higher priority on the GHFS voice circuits than do the EAM transmissions as an EAM transmission will be terminated in midstring in order to immediately transmit these "SKYKING" DNA broadcasts.


04 Apr 2005 Update:

 The information in the above paragraph was written in 1998 and will remain unaltered in the interest of "history”; however, unlike the subtly changing information in the earlier EAM paragraph, there are some notable changes in the FOXTROT broadcasts since 1998.

  • Prior to 1992 all FOXTROT broadcasts were initiated with aliased echo rotation callups similar to that described above.
  • For a short time in the second half of 1992 (which represents the activation of the USSTRATCOM following the deactivation of SAC) the echo rotation callups were "in the clear."
  • From maybe late in 1992 (or early 1993 lost in the fog of memory) the GHFS went back to aliased callup echo rotations as described in the above paragraph.
  • In the 21 century the GHFS ceased to exist, replaced with the HF-GCS.

 In the immediate post 11 September 2001 time period, during the run up to the purging of the Taliban from Afghanistan, the echo rotations appeared to go through a transformation. They were no longer aliased and at least two new stations were added to the echo rotation call up: DIEGO GARCIA and for a brief period CYPRUS FLIGHT WATCH. After this conflict ALL requests for echo rotation disappeared from the FOXTROT broadcasts, and it remains that way into CY 2005.


Further detailed information can be found from the following sources:


Hobby sources:

  1. Ary Boender's "Numbers & Oddities" column in the July 1995 (FOXTROT broadcasts) and August 1995 ("EAMs") WUN Newsletters (both newsletters are now "archived" at the WUN web site to save drive space - wunv1n7.zip and wunv1n8.zip) - a short overview of how these broadcasts 0manifest themselves on various HF frequencies.
  2. The December 1994 issue of Monitoring Times containing the "Utility World" column of Larry Van Horn, titled "US Air Force Global High Frequency (HF) System." A concise overview of the GHFS, and the traffic contained on the GHFS.
  3. The September 1995 issue of Monitoring Times containing the "Utility World" column of Larry Van Horn, titled "What's the meaning behind the messages." An overview of the "message" traffic heard on the GHFS and the NIGHTWATCH net.
  4. "The Aeronautical Communications Handbook - HF Edition" by Robert E. Evans; 1989 (and out of print, I believe); pages 7.11-7.13. Written while the Strategic Air Command was still in existence, so most of the information is out of date in it's details, but apparently not in it's overview of the EAMs.

"Academic" sources:

 There are no known public sources for detailed descriptions of these strings, but there are a number of books and papers published that cover this topic in broad strokes (and, which I suspect are in many ways greatly out of date - I've found nothing that covers the post 1992 strategic world in a way that is as detailed as they cover the pre 1992 world. It may be too early to do so, as it is probably still in transition). Some examples follow:

  1. "The Logic of Accidental Nuclear War" by Bruce G. Blair; The Brookings Institution; 1993 (still in print); ISBN 0-8157-0983-8 (paper). There are numerous additional sources listed within the extensive "notes" section of this book. The notes section also contains detailed information that covers the uses of these messages.
  2. "Strategic Command and Control - Redefining the Nuclear Threat by Bruce G. Blair; The Brookings Institution; 1985 (still in print as of the middle of 1996); ISBN 0-8157-0982-X (hardbound). Much of this information covers what is now the foundation for today's strategic world, but I suspect that many of the specific details covered in the book are now greatly altered, maybe beyond recognition (such as the integration of the USN into much of the then SAC-centric activity in his book.)
  3. "Global Zero Alert for Nuclear Forces" by Bruce G. Blair; The Brookings Institution; 1995 (May or so, and still in print); ISBN 0-8157-0941-2. The only "book" (it's actually an "occasional paper" of 108 pages) in this group that can be said to be up-to-date in the post 1992 strategic world. On EAMs, in particular see pages 59-60.
  4. "Guarding the Guardians: Civilian Control of Nuclear Weapons in the United States" by Peter Douglas Feaver; Cornell University Press; 1992 (out of print unfortunately). Mostly covers PAL (Permissive Action Link) locks but has an overview on EAMs throughout the book.
  5. "Dark Sun - The Making of the Hydrogen Bomb" by Richard Rhodes; Simon and Schuster; 1995 (still in print); ISBN 0-684-80400-X. Page 573: "..SAC routinely transmitted DefCon increases as unclassified messages until 1972." Question: what happened after 1972? - "SAC routinely transmitted DefCon increases as classified messages"?
  6. The 10 May 1976 issue of "Aviation Week and Space Technology", devoted almost entirely to the Strategic Air Command. Written during the "Alpha Net" days of OFFUTT/BARKSDALE/WESTOVER/MARCH but has information that might still apply in some aspects 20 years later (probably modified.)
  7. The Winter 1996 (Volume 27) issue of "World Air Power Journal" devoted to the B-52H with a long article beginning on page 54 written by Robert F. Dorr and Brian C. Rogers. See page 89 for a description of the receipt and authentication of an emergency war order onboard an airborne B-52H.



  1. "The Hunt for Red October" by Tom Clancy; Naval Institute Press; 1984 (still in print); ISBN 0-87021-285-0. Pages 65-66 (hardcover) for EAM information; and page 68 (hardcover) for "traffic analysis" fans.
  2. "Arc Light" by Eric L. Harry; Simon and Schuster (his editor was also Rhodes' editor on "Dark Sun"); 1994 (Aug); ISBN 0-671-88048-9. The author gets to engage the Midnight Express (see the "Logic..." book) and run his SIOP, in a probable pre-92 way though.


04 April 2005 update to information published on 02 September 1998 and 30 March 2005

Jeff Haverlah