A Compilation of Extracts
Edited by Jerry Proc

A great deal of material has been written about the Washington-Moscow Hot Line since it first went into service in 1963. It is the author's intent to summarize the history of the Washington-Moscow Hot Line using publically available sources. As in any research of this nature, minor conflicts of information arise. Every effort has been made to minimize these situations.


David Kahn's, "The Codebreakers", 1967, p 715-716 provides an excellent summary of the how the Hot Line came into existence.

"As a result of the Cuban missile crisis the long, talked-about "hot line" between Washington and Moscow was to become a reality. On 20th June, 1963, at Geneva, Switzerland , the United States and the Soviet Union signed a Memorandum of Understanding that set up a duplex cable circuit routed from Washington-London-Copenhagen-Stockholm-Helsinki to Moscow for primary political communications and a duplex radio circuit routed from Washington to Tangier to Moscow for service communications and as a back-up.

"In our negotiations," wrote Brigadier General George P. Sampson, deputy director of the Defense Communications Agency and chief technical member of the American negotiating team at Geneva, "it was obviously recognized early in the game that some steps had to be taken to insure the privacy of the communications and quite as obviously the technique employed would have to be one generally known throughout the world. It was with this background that the method for privacy which was adopted was suggested and, if my memory serves me correctly, its first mention was by the U.S. side although the general subject had been alluded to by both groups."

The method to be used was one-time tape. Section 4 of the annex to the memorandum stated: "The USSR shall provide for preparation and delivery of keying tapes to the terminal point of the link in the United States for reception of messages from the USSR. The United States shall provide for the preparation and delivery of keying tapes to the terminal point of the link in the USSR for reception of messages from the United States. Delivery of prepared keying tapes to the terminal points of the link shall be effected through the Embassy of the USSR in Washington (for the terminal of the link in the USSR) and through the Embassy of the United States in Moscow (for the terminal of the link in the United States).

For its one-time tape hardware, the US would employ the ETCRRM II, or Electronic Teleprinter Cryptographic Regenerative Repeater Mixer II. One of many 'one-time' tape mechanisms sold by commercial firms, it was produced and sold for about $1,000 by Standard Telefon Kabelfabrik of Oslo, the Norwegian subsidiary of International Telephone and Telegraph Corporation, the same company  which installed the American terminal in the National Military Command Center deep within the Pentagon. It has four teleprinters -- two with English alphabet and two with Russian -- and four associated ETCRRM II's . In Moscow, the terminus was installed in the Kremlin, near the office of the Premier".

The Washington to London portion of the link was carried over the TAT-1 (Transatlantic No. 1), the first submarine transatlantic telephone cable system. It was laid between Gallanach Bay, near Oban, Scotland and Clarenville, Newfoundland between 1955 and 1956 and was inaugurated on September 25, 1956.


This was the Washington side of the hotline. In the foreground, an Air Force S/SGT is examining tape from the Teletype Corp. Model 28 ASR Automatic Send-Receive teletype (ASR) which is fitted with an "under the dome" reperforator. The reperforator is separate from the keyboard,  printer,  and T-D (reader), and was usually plugged into a patch panel. Directly behind the standing man is a  Teletype Model 28 ASR. Also pictured are two identical sets of equipment at the right side:  two Russian T63 teleprinters and two ETCRRM  crypto units. The above configuration would have been duplicated in Moscow.  It sure looks crammed in that room!  (NSA photo enhanced by Jerry Proc)

ETCRRM  (Photo by Jerry Proc)
Four ETCRRM's were used on the Washington/Moscow Hotline when it was first installed - two in Washington, two in Moscow. It is presumed that one unit was a spare at each end. 

Invented by the Norwegian Army Signal Corps in 1950, this machine uses the Vernam stream cipher method (circa 1919) in which plain text message is eXclusively OR'ed with a random or pseudo random stream of data of the same length to generate the ciphertext. Once a message was enciphered the keytapes were destroyed. At the receive end, the process was reversed. An identical keystream tape was used to decode the message. 

Internally the machine uses ECC91 (6J6) tubes, relays and selenium diodes for implementing logic functions. The machine was designed for low speed, start-stop asynchronous applications in conjunction with a teleprinter, reperforator or T-D (Transmitter-Receiver).

Close ups of the T63 SU12 teletype which is on display at the National Cryptologic Museum. This teleprinter was used on the Hot Line from 1963 to 1980. The placard at the NSM says the T63 was made by Siemens. That is incorrect. The machine was a T-63 made by VEB RFT Messgerätewerk Zwönitz (probably in a former Siemens factory). The T-63 was based on the earlier RFT T-51 that in turn was an East German copy of the Siemens T-37. It is also known as T63/SU12 and as T63/RU. Additional info on the T-63 can be found here
(All photos in this table courtesy NSA) 

The hotline became operative August 30, 1963. Because the link was not in constant use it had to be tested each day. This called for creative dialogue between two archenemies. Poems and stories of all sorts were exchanged. Sometimes baseball game scores from the American side or excerpts from Ivan Turgenev's "Notes of a Hunter" on the Soviet side were transmitted. However, some of the exchanges caused puzzlement on the Soviet end. One day, Andrei Gromyko asked Dean Rusk 'What does it mean when your people say, "the quick brown fox jumped over the lazy dog?"

In the beginning, no official substantive messages were  passed over its wires, but it reportedly was used the day of President Kennedy's assassination. It remained in state of readiness, as  President Kennedy said when inaugurating it, "to help reduce the risk of war occurring by accident or miscalculation." The keying tapes that help prevent a fake message and assure the privacy of delicate negotiations were provided by NSA's Office of Communications Security.

All messages from the U.S. to Russia are transmitted in English, using the Latin alphabet while all messages from Moscow to Washington are transmitted in Russian, using Cyrillic characters. The translation is always done at the opposite end, to preserve the nuance of the message.

The Kremlin first used the Hotline in 1967 during the six-day Arab-Israeli war to prevent possible misunderstanding between the naval groups of the Soviet Black Sea Fleet and the US 6th Fleet, which approached each other dangerously closely in the Mediterranean.


Both the landline and radio paths were vulnerable and could have been interrupted or denied by an act of sabotage or interference . Official concern in the US and the Soviet Union grew when the prime link was severed on several occasions. A Danish bulldozer operator once cut the line near Copenhagen. A Finnish farmer once plowed it up. A fire in a Baltimore Maryland manhole took it out of service temporarily.


The white paper "Origins, Use and Development of Hotlines" addresses the myth of telephones on the Hot Line.  "One of the lasting myths surrounding the Hot Line is that it consists of a telephone link. This was considered by both superpowers but there were strong arguments against using a telephone connection. All parties concerned preferred a teletype link. The Americans pointed out that a teletype system on a reserved line could have dual capabilities and be used for voice communications should that prove desirable.

Nevertheless, the image of the hot line as a telephone link has prevailed. This misunderstanding is not confined to the public. When it was suggested in the U.S. State Department in 1983 that speech facilities should be added to the hot line, many officials believed it already had a telephone as seen in the movies!

It is not difficult to imagine why this myth has persisted. The telephone is the fastest and most common communication link and has proved itself an important tool of diplomacy since the 1950s, when phone services were made more reliable by the introduction of submarine cables. Diplomatic communications were previously confined mostly to telegrams, which have continued to be the most important communications link of diplomacy. With improved communications , heads of government or ministers have the possibility to pick up a telephone and instantly or within minutes get their counterparts on the line. The idea of heads of state salvaging world peace by simply dialling and dialoging with a counterpart captures the imagination but it's an unrealistic scenario. It is the speed of this form of communication which makes it an unsuitable tool for crisis management.

The argument against using a voice emergency communication link is both technical and political. The Hot Line was designed to be used in the gravest situations, which make exchanges over a hot line even more precarious if done by telephone. Telephone diplomacy can be a double-edged sword in communications between adversaries and is more suitable in relations between states on friendly terms. The U.S. 1962 Working Paper pointed out some of the serious disadvantages. It was more likely to lead to inadvertent error either through lack of precision in reception or through incorrect translation. Misunderstanding, because of these reasons or simply any slip-ups of the tongue or ill-considered statements will be easily mended or instantly forgiven by friends but can make relations even more strained between hostile states.

From a practical point of view, there was also the problem of translation. A vocal Hot Line required conversations to be translated instantaneously at both ends. Even though speed of communication was of utmost importance in times of crisis, accuracy in translation could not suffer because of it. Using a telephone link could therefore increase the possibility of misunderstanding rather than eradicate it. Organizing translation was no easy matter as was discovered when the London-Moscow hot line was discussed in 1966. Translators had to be on call 24 hours a day, which meant their residence had to be close to Whitehall. This led to discussions about getting two bachelors to live in a  flat or a hotel room nearby.

The spontaneity of the telephone conversation makes it unpredictable and therefore impossible to script. In times of crisis, people are under duress and pressure. Instantaneous and ill-considered remarks are dangerous. During conversations between heads of state in normal times, this can be an advantage depending on the situation, topic and the person's ability to think on his feet. However in times of crisis, mistakes come at a high price and none higher than the risk of a nuclear war. The words of a head of state carry a lot of weight and are not easy to retract. Bilateral relations require well thought out messages and responses. The teletype minimizes the risk of personal friction between heads of state. Exchanging written messages gives both parties time for reflection, to analyze and respond or even to let off some steam. The telephone does not allow this latitude but on the contrary compels a response of some sort, which can result in a misguided reply or a misunderstood answer.

This does not mean that translation or interpretation of printed messages is always reliable. President Carter's attempt to use the Hot Line to bypass diplomatic channels to get straight to Brezhnev during the SALT-2 discussions proved disastrous. The KGB translators on duty were not highly qualified and unfamiliar with the jargon of strategic negotiations. Therefore their translation of Carter's message was marred by many inaccuracies and rough spots which did not exactly facilitate a good reception by Soviet leaders.

Nevertheless, oral communication is less reliable than the written record and leaves more room for speculation than written exchanges. Furthermore no time is lost on formalities or the danger of verbal decoys or stalling. In a crisis, a number of people besides the head of government are taking part in forming policy and determining actions. The flow of information must be efficient and the quickest and most reliable way of distributing this kind of information is in written form.

To read the entire white paper on " The Origins, Use and Development of Hot Line Diplomacy by þór Eglisson", please select this link.


According to Viktor Sukhodrev, the Kremlin interpreter who had worked with Khrushchev and Brezhnev, "At first there was no telephones; there were only simple teletypes, like at any common telegraph station. The Soviet leaders had to wait while their words were translated into English and sent by operators to Washington."

An excerpt from the NADCOMM web page summarizes the upgrades to the Hot Line. "During the SALT-1 treaty discussion in the early 1970s, the Soviets showed interest in modernizing the Hot Line as a result of their concern over their strained relations with China. Advances in satellite communications technology that had occurred since 1963, moreover, offered the possibility of greater reliability than the arrangements originally agreed upon. On September 30, 1971, an agreement was signed in Washington to modernize the Hot Line.  The agreement, in its entirety, is provided here.

The first stage of modernization was launched in 1971 and lasted until January 1978. Two American Intelsat satellites  plus two Soviet Molniya II satellites on a highly elliptical orbit became the primary links between Washington and Moscow. The United States was to provide one circuit via the Intelsat system and the Soviet Union would provide the other a circuit via its Molniya II system. A system of multiple terminals was installed in each country. The original teletype circuits were retained as a backup to the satellite links but the Washington-Tangier-Moscow radio circuit was terminated. A provision in the agreement said that the original terrestrial circuits were to be maintained until it was agreed that the operation of the satellite circuits made them no longer necessary. Because neither leader was always in their capital, the terminals needed to be more mobile. Running the Hot Line over a satellite link instead of a landline served this purpose well as making it less vulnerable in wartime.

hotline_ft_ detrick_1976.jpg
The Fort Detrick earth station as seen in 1976.  (US Army photo via George Mace).

In October 1972, the U.S. Army Satellite Communications Agency awarded a contract to the Radiation Division of Harris-Intertype Corporation to build the US terminus a complete Earth Station on a 15-acre site at Fort Detrick, Maryland. This earth station was the USA's part of a direct communications link  via satellite between the respective heads of state in the White House and the Kremlin. Radiation's Direct Communications Link (DCL) Hotline program team turned the key of the new facility in the spring of 1974 and also operated and maintained the station and its equipment through 1977. (Photo by Tim Tyler)
Here are some facts from the technical briefing when the new US earth station station was opened at Fort Detrick:
The DCL Earth Station consisted of two identical communications systems that provided simultaneous transmission and reception of C-band, FM-modulated signals through 60-foot tracking and communication antennas. During the 8-hour period in which each satellite was mutually visible between Washington and Moscow, its pilot signal was autotracked by the two DCL antennas. Shortly before mutual visibility was lost, one antenna was commanded under computer control to the coordinates where the next satellite in sequence was to be acquired. Following automatic acquisition and the establishment of the communication circuit through the new spacecraft, the original circuit was broken and the second antenna moved over to provide backup. An interruption of communication for a period exceeding 5 milliseconds constituted a failure. The Mean Time Between Failures (MTBF) was greater than 835 hours. The mean time to restore one signal route to operation following a failure was not to exceed 15 minutes. Corrective maintenance took less than 45 minutes for 90 percent of all failures.

Other minor but practical improvements have also been made on the "Molink", the nickname used by the American technicians who maintained the Hot Line. Clocks were placed on each end showing the time of day in the other capital. This would prevent any confusion as to the time of day any message was sent.

In May 1983 President Reagan proposed to upgrade the Hot Line by the addition of  high-speed facsimile capability. This proposal was recommended to the President following a study of possible initiatives for enhancing international stability and reducing the risk of nuclear war. As a result of this initiative, negotiations between the United States and USSR on improving bilateral communications links opened in Moscow in August 1983. Subsequent rounds were held in Washington in January 1984, in Moscow in April 1984, and again in Washington in July 1984. Those discussions resulted in an accord, signed on July 17, 1984, to add a facsimile transmission capability to the Hot Line. This capability became operational in 1986. One web document indicates that voice capability (telephone) was also added in the 1986 modernization but there is no way to corroborate at this time.

As of 1986, the Hot Line consists of two satellite circuits and one wire telegraph circuit. The Soviets used stationary Gorizont-class satellites in the Statsionar system to replace the Molniya II satellites, also with a high-speed facsimile capability. Terminals linked to the circuits in each country are now equipped with teletype and facsimile equipment. Facsimile machines permit the heads of government to exchange messages far more rapidly than they could with the previously existing teletype system. They can also send detailed graphic material such as maps, charts, and drawings by facsimile".

After several years of testing and use, the fascimilie equipment proved to be so reliable that the teletype circuits were turned off in 1988.

In 2007, the Moscow-Washington hotline was upgraded to a dedicated computer network, linking the Washington and Moscow terminals. This network runs over the two existing satellite links and a new fiber optic cable, which replaced the old back-up cable link. Commercial software is used for both chat and email. The chat function is used for coordination of link operations, while email is used for sending the actual messages. Transmission is nearly instantaneous. These capabilities became operational on January 1, 2008

If any reader can provide any further updates to this web document, please contact:

An MS-Word copy of this document has been translated into Italian by Nico Michelini, IV3ALA.

Credits and References:

1)  David Kahn, "The Codebreakers", 1967, p 715-716
2) Matt R <matt_crypto(at)>
3) Gregory W. Moore <gwmoore(at)>
10) Tim Tyler <nightwatch01(at)>
11) George Mace <gmace8(at)>
12) Nico Michelini   <iv3ala(at)>
15) Paul Reuvers <info(at)>

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Oct 4/16