Naval Cryptology and the Cuban Missile Crisis

The following article series appeared on Station Hypo and is republished with permission.  

By David T. Spalding

The Vindication of Right: Battlespace Awareness in the Cuban Missile Crisis


“Our goal is not the victory of might but the vindication of right-not peace at the expense of freedom, but both peace and freedom, here in this Hemisphere and, we hope, around the world. God willing, that goal will be achieved.” — JFK

Such was the goal of President John F. Kennedy in the Cuban Missile Crisis on the eve of October 22, 1962 – “the vindication of right”.  In the preceding months and years, signals intelligence — provided in large part by cryptologists of the Naval Security Group — revealed that the Soviet Union had been building up troops, aircraft, and air defense and missile sites in Cuba under the guise of self-defense.  When intelligence indicated that the buildup was more than just defensive in nature, JFK put the Soviet Union on notice in front of a watching world.

On the brink of thermonuclear war, the President of the United States initiated a quarantine in the waters off of Cuba to intercept, search, and turn back USSR cargo vessels destined for Cuban ports.  Russia responded with rhetoric of open defiance.  The days that followed would prove that their bark was bigger than their bite.  As early as October 23rd, U.S. Navy listening posts and direction finding stations along the Atlantic periphery collected on, and geo-located, Soviet ship-ship and ship-shore communications, indicating that the Soviet vessels had stopped or reversed course prior to reaching the ring of surface ships forming the blockade.  Communications intelligence collected by naval cryptologists also provided insight into Soviet and Cuban commanders’ intentions, force alert posture and levels, and previously unidentified Soviet submarine activity.  Though tensions would remain high for some time, the potential for total war between the world’s two superpowers had been averted.

Fifty years ago, the short narrative above would have said nothing of the role of signals intelligence.  Today, we know more.  In 1998, 35 years after the crisis, the National Security Agency declassified many documents and reports that revealed the critical role that naval cryptology played not only in defusing the crisis, but in providing Battlespace Awareness to decision makers as early as 1960 and continuing on through the end of the crisis.

Fast-forward to present day — the Navy’s Strategy for Achieving Information Dominance 2013-2017 lists Battlespace Awareness as one of its three fundamental capabilities along with Assured Command and Control and Integrated Fires.  As described in the strategy, Battlespace Awareness “is the traditional mission of the Information Dominance Corps and the constituent components of meteorology, oceanography, intelligence, cryptology, communications, networks, space, and electronic warfare.” 

Though the Cold War would continue for nearly three more decades — Battlespace Awareness — providing commanders with persistent surveillance of the adversary’s activities, penetrating knowledge of the USSR’s capabilities and intentions, and expertise within the electromagnetic spectrum enabled those very commanders to make informed decisions ensuring that the war did not progress from cold to hot.

*In the pages below, are short vignettes and historical documents related to the signals intelligence and cryptologic efforts which provided Commanders with time-critical Battlespace Awareness — contributing significantly to the de-escalation of one of the potentially most dangerous stand-offs in history.

Thirteen Days? The Naval Security Group in the Cuban Missile Crisis


History has recorded the Cuban Missile Crisis as having occurred October 16, 1962 – October 28, 1962:  a total of thirteen days.  October 16th being the day after photographic intelligence confirmed the existence of Soviet medium-range ballistic missiles in Cuba and October 28th being the day Khrushchev directed the dismantling, and return, of offensive weapons in Cuba.   In reality, the story began long before October 1962.

Two years earlier in September 1960, communications intelligence, collected by the National Security Agency along with its three Service Cryptologic Agencies – to include the Naval Security Group, provided the first indications that Soviet arms were being transported to Cuba via multiple cargo ships.   Similar reports revealed high-level visits from a Soviet arms export chief to Havana as well as the purchase of Soviet helicopters by Cuba.

In 1961, persistent surveillance would further confirm suspicions of a significant Soviet military buildup in Cuba.  In February, signals intelligence indicated Cuban pilots were training in Czechoslovakia; in May, communications intelligence revealed Cuban air force personnel were learning Russian; in June, radars were being installed for possible use with artillery units…all the while Soviet cargo ships continued to dock in Cuban ports and unload their cargo under the cover of night. 

Continued collection efforts by the Naval Security Group, et. al., in 1962 would paint an even clearer picture of Soviet capability and intent in Cuba.  Of particular note were successes in the area of electronic intelligence.  In May of 1962, electronic intelligence provided the first evidence of the use of SCAN ODD, a Soviet airborne intercept radar associated with MiG-17 and MiG-19 aircraft, in Cuba.  Later in the year, electronic intelligence would provide another key development.  According to the Center for Cryptologic History’s NSA and the Cuban Missile Crisis:  “Human sources and photography could spot SA-2s, but signals intelligence would provide the first indicator of their operational status… NSA reported the first operation of a SPOON REST radar, associated with the SA-2.  The SA-2 was operational and could shoot down a U-2.  Subsequent overflights would be at risk.”  The Department of Defense was not going to sit idly by while Khrushchev continued to increase his footprint in the western hemisphere.  

On 16 July 1962, the Secretary of Defense, Robert McNamara, directed an increase in the signals intelligence program to combat the Cuban problem.  Three days later, in a Memorandum for the Secretary of the Navy, the Naval Security Group (OP-94G) was specifically directed to “realign its resources to provide greater coverage of Cuba in response to highest priority intelligence requirements.” 

The memorandum recognized that such realignment would have some degree of impact on naval intelligence collection and acknowledged that loss would occur in other collection efforts.  To try to mitigate this deficit, the Naval Security Group would coordinate with DIRNSA in utilizing personnel from her sister agencies — the Air Force Security Agency and the Army Security Agency – to man her stations.  The memorandum also discussed several other measures by which the Naval Security Group would meet the SECDEF’s requirements:

(1) Provide an additional 20 officers and men to two undisclosed locations.

(2) Extend the interim shipborne intercept capability (USS Oxford) through approximately Dec 1962.

(3) Arrange directly with Commander, Military Sea Transportation Service (MSTS) — now known as Military Sealift Command (MSC) — for an MSTS ship to relieve USS Oxford to continue the SIGINT effort off Havana no later than 1 Dec 1962.

What most label as a crisis is more accurately described as a persistent effort against a formidable adversary over the course of two years.  Such was the experience of the cryptologists of the Naval Security Group.  Their round-the-clock efforts helped to ensure that the crisis was not unnecessarily prolonged beyond what most remember as thirteen days. 

USS Oxford: The Largest Producer of SIGINT in the Cuban Missile Crisis


The USS Oxford (AG 159) was originally commissioned a Miscellaneous Auxiliary ship in July 1961 in New York.  She was immediately outfitted to participate in the National Security Agency’s Technical Research Ship (TRS) program — though she would not be redesignated an Auxiliary Technical Research Ship (AGTR-1) until years later in 1964. 

The Center for Cryptologic History’s Almanac 50th Anniversary Series article, “The TRS Program Part I:  The Beginning,” describes perfectly the Oxford’s significant contribution to the Cuban Missile Crisis.

The Oxford was officially known as a Technical Research Ship.  Its initial mission was a training cruise.  This gave the crew a chance to familiarize themselves with equipment on board and to identify any problems with the newly refurbished, redesigned ship before traveling to the Middle East.  Although several features were identified that required change or improvement, overall the test proved to be a great success.  For example, the Oxford recorded frequencies and collected a large number of other transmissions.  As the capabilities of the Oxford became clear, the list of potential targets for these ships quickly expanded to include countries all over the globe.

In August 1962, as relations between the United States and the Soviet Union over Cuba grew increasingly tense, the Oxford was diverted to the Caribbean.  Its mission was to collect the communications coming out of Cuba, used by both Soviet and Cuban entities.  The Oxford proved to be the largest producer of SIGINT during the Cuban Missile Crisis [emphasis added].  The communications it collected provided a great quantity of information which, when combined with the photographs from the U2 overflights, provided a very good picture of what was happening in Cuba.

USS Oxford’s success in the Cuban Missile Crisis “demonstrated the value of the TRS program” and paved the way for naval cryptology aboard future Technical Research Ships:  Georgetown, Jamestown, Muller, Belmont, and Liberty.

Find and Fix: Direction Finding in the Cuban Missile Crisis


The high frequency direction finding (HFDF) fix in the above message was one of many prosecuted by dozens of U.S. Navy, British, and Canadian direction finding stations in the Atlantic periphery on the days following the President’s initiation of a naval blockade.  Matthew M. Aid, in his book, The Secret Sentry, writes:

“The two dozen or so U.S. Navy, British, and Canadian direction-finding stations ringing the Atlantic continuously monitored every radio transmission going to or from the twenty-two Soviet merchant ships approaching the Cuban quarantine line, in order to track the movements of the Russian ships…  The U.S. Navy’s direction-finding stations began reporting to NSA that their tracking data indicated that some of the Russian merchant ships had stopped dead in the water, and that it seemed that at least eight of the ships had reversed course and were headed back toward Russia.”

The value in such collection is not in the finding and fixing of the ships’ positions alone, but rather in the ability ofsuch information to indicate that the ships had either stopped or reversed course.  That is actionable intelligence.

Such knowledge affords key leadership the time and the ability to make informed decisions.  The message above, combined with many others like it, painted a clear picture of the Soviet’s intentions to not challenge the blockade in full force.

Such is one of the primary roles of a naval cryptologist — to find and fix the adversary.  The fix part of this equation is primarily accomplished via direction finding.  As demonstrated, direction finding provides specific actionable intelligence to warfighters on the ground, in the air, at sea, and on our networks.  It contributes directly to providing Battlespace Awareness to the operational commander.  Battlespace Awareness is, amongst other things, an understanding of when, where, and how our adversary operates.  This understanding, combined with persistent surveillance, penetrating knowledge, and expertise within the electromagnetic spectrum provides the commander with time and “the target acquisition and targeting solutions necessary to apply force, both kinetic and non-kinetic.”

17 November 1962: A Letter of Commendation and Thanks

Blake and Dennison

The following is an excerpt from a previously classified letter written by Admiral Robert Dennison (CINCLANTFLT, 1960-1963) to Lieutenant General Gordon A. Blake (DIRNSA, 1962-1965) on 17 November 1962 regarding the contribution of SIGINT during the Cuban Missile Crisis.

“I should like to take this opportunity to mention the very significant contribution which SIGINT in general – and the National Security Agency in particular – have made toward support of Atlantic Command.  The unique and vital intelligence made available as a result of the national SIGINT effort frequently finds its end use and final justification at the level of the Unified Commander.  In the present situation SIGINT has been one of the most important single factors in supporting our operations and improving our readiness.  Your fine support is much appreciated.” 

DIRNSA responded:  “While you mentioned NSA in particular…the Naval Security Group…deserve[s] a lion’s share of the credit for their work in the fields of collection and direct processing to our customers.  I have taken the liberty of passing on your kind remarks to both NSA personnel and the Service Cryptologic Agencies as kindred elements of our SIGINT team.”

*The letter can be read in full here.



LCDR David T. Spalding is a former Cryptologic Technician Interpretive.  He was commissioned in 2004 as a Special Duty Officer Cryptology (Information Warfare/1810) and currently serves as the Officer in Charge of Navy Information Operations Detachment Kaneohe Bay, Hawaii.


The Secret Sentry:  The Untold Story of the National Security Agency, Matthew M. Aid (pp. 74-77)

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