Contact: Kelsey Davenport, Director of Nonproliferation Policy , (202) 463-8270 x102
Updated: November 2012
A hotline is a quick communication link between heads of states, which is designed to reduce the danger of an accident, miscalculation or a surprise attack, and especially an incident that might trigger a nuclear war.
1963 Memorandum of Understanding
On June 20, 1963, the United States and the Soviet Union signed the "Memorandum of Understanding Between the United States of America and the Union of Soviet Socialist Republics Regarding the Establishment of a Direct Communications Link," also known as the hotline agreement, which was designed to help speed up communications between the two governments and prevent the possibility of accidental nuclear war. It is no coincidence that the agreement came just a few months after the October 1962 Cuban missile crisis, when the United States and the Soviet Union came to the brink of nuclear conflict. The new agreement was designed to forestall such a crisis in the future.
The hotline agreement held each government responsible for the arrangements for the communications link on their territories respectively. The hotline would comprise of a full-time duplex wire telegraph circuit with two terminal points with teletype equipment routed between Washington and Moscow via London, Copenhagen, Stockholm, and Helsinki and a full-time duplex radiotelegraph routed through Stockholm-Helsinki-Moscow. In case the wire circuit was interrupted, messages would be transmitted via radio circuit.
It is a misleading belief that the hotline was a red telephone that sat in the Oval Office of the White house. The first generation of the hotline had no voice element and actually resided in the National Military Command Center in the Pentagon. “It was decided that if the leaders spoke over the telephone they would have to rely too heavily on rapid translation. Printed messages would provide greater clarity and give either party time to reflect before replying.” The Washington–London link was originally carried over the TAT-1, the first submarine transatlantic telephone cable. Such a design prevented spontaneous verbal communications, which could lead to misunderstanding and misperceptions.
A secondary radio line was routed between Washington, D.C. and Moscow via Tangier. American teletype machines had been installed in the Kremlin to receive messages from Washington; Soviet teletypes were installed in the Pentagon. Both nations also exchanged encoding devices in order to decipher the messages. The transmission of a message from one nation to another would take just a few minutes. The messages then were translated.
First Use of the Hotline
The hotline significantly reduced the time required for direct communication between the heads of the two governments from hours to minutes. In August 1963, the system was ready to be tested. On August 30, 1963 the United States sent its first message to the Soviet Union over the hotline: "The quick brown fox jumped over the lazy dog's back 1234567890."
The message used every letter and number key on the teletype machine in order to see that each was in working order. The return message from Moscow was in Russian, but it indicated that all of the keys on the Soviet teletype were also functioning.
The hotline was first used by the United States and Russia in 1967 during the Six Day War between Israel, Egypt, Jordan and Syria to clarify the intentions of fleet movements in the Mediterranean that could have been interpreted as hostile. Thereby, the Soviet Union and the United States intended to reassure each other that they did not wish to be militarily involved in the crisis and did not make efforts to bring about a ceasefire. Throughout the duration of the Six Days War, the two sides used the hotline almost two dozen times for a variety of purposes. Richard Nixon also used it during the Indo-Pakistani War of 1971 and again during the 1973 Arab-Israeli War. During the Reagan Administration, the hotline was used several more times. However, an official listing of the instances when the states used the hotline never has been released to the public.
Modern Version of U.S.–Russian Nuclear Hotline
In the 1970s, the hotline was improved with better technologies. In 1971, the two sides signed the hotline modernization agreement. Under this agreement, the United States was to provide one circuit via the Intelsat system, and the Soviet Union a circuit via its Molniya system. The 1963 radio circuit was terminated, and the wire telegraph was retained as a back-up.
The hotline had undergone several more upgrades to include facsimile transmission and was renamed as the Nuclear Risk Reduction Center (NRRC) in 1987. The Center used both U.S. and Soviet satellites to transmit facsimile data. Later that year, the Intermediate Range Nuclear Forces Treaty (INF) was signed making the NRRC system the official channel for all data exchanges and notifications required under the treaty. Use of the NRRC network was expanded even further with the signing of START I in 1991, and its entry into force in 1994. 
"Although used primarily for the exchange of notifications under existing bilateral and multilateral treaties, the NRRC has periodically proved its use in other areas as well. In January 1991, goodwill notifications were used to exchange information on the re-entry of the Salyut 7 space station. Later that same year the NRRCs served as a means of emergency communications during a major fire in the U.S. Embassy in Moscow." The hotline between Moscow and Washington still exists, despite improved relations and the end of the Cold War. Over the years, it has been upgraded keeping apace with the technological development. The former C.I.A. director and defense secretary, Robert Gates, has said that the hotline will remain an important tool for "as long as these two sides have submarines roaming the oceans and missiles pointed at each other." 
Other Bilateral Hotline Agreements
Once the hotline between Washington and Moscow proved to be useful, other states established hotlines. In 1966, France signed an accord establishing a direct communications link between Paris and Moscow. Under the 1967 British-Soviet agreement, a direct communications line was set up between Moscow and London.
Russia–China Nuclear Notline
In 1998, Beijing established head-of-state hotlines with Russia and the United States. In April 1996, during Russian President Yeltsin’s third summit meeting in Beijing, the two sides agreed to maintain regular dialogues at various levels and through multiple channels, including a governmental telephone hotline. On May 3, 1998, a hotline between China and Russia finally began operating. This is the first time Beijing has established a hotline with the head of a foreign state. Ten years later, in March 2008, a hotline between the Chinese and Russian Defense Ministries was established to enhance bilateral cooperation between the two states. The Russian and Chinese were exchanging their views on the international and regional situation as well as other issues of common concern.
U.S.–China Nuclear Hotline
In April 1998, China’s minister of Foreign Affairs Tang Jiaxuan and U.S. Secretary of State Madeleine Albright signed an agreement to establish a hotline between the governments of the two countries. The hotline was activated during President Clinton’s visit to China in June 1998.
India–Pakistan Nuclear Hotline
In 2004 India and Pakistan agreed to set up a telephone hotline between the most senior officials in their foreign ministries respectively to prevent a nuclear incident. The two states have fought three wars since they both gained independence in 1947, and were dangerously teetering on the brink of nuclear conflict in 2002. In 2004, along with the establishment of the hotline, both states limited command and control structures, and reaffirmed that each side would continue to uphold the moratorium on nuclear tests.
After the 2008 Mumbai attacks from Pakistan had upset the relations between the two states. Three years later in 2011, India and Pakistan set up a “terror hotline”. The hotline warns each party state of possible militant attacks and moves them to restore the trust between each other.
South Korea–China Defense Hotline
In 2008, South Korea and China set up telephone hotlines between their navies and air forces to help prevent accidental clashes. However, the hotline has reportedly been used only a handful of times, and never to test procedures in a simulated crisis. South Korea and China agreed on July 31, 2012 to establish an additional high-level hotline between their defense chiefs in an effort to strengthen military cooperation, officials in Seoul said.
In April 2010, the prime ministers of China and India agreed to det up a hotline to better avoid flare-ups over a longstanding border dispute across the Himalayas, and to strengthen their diplomatic ties. "The agreement to establish a hotline is an important confidence-building measure and it opens up a direct channel of communication between the two leaders," India's foreign secretary, Nirupama Rao, told reporters ar a press conference in Beijing.
A hotline between the Vietnamese and the Chinese Mnistries of Foreign Affairs was established in March 2012. In their talk on the line, the ministers affirmed their will to strengthen the Vietnam-China comprehensive strategic cooperative partnership. 
Research Assistance by Daria Medvedeva
1. The text of the memorandum: http://www.state.gov/t/isn/4785.htm
2. Blacker C.D., Duffy G. (Stanford Arms Control Group). “International arms control”, Standford University Press. 1984.
3. “August 30, 1963: The U.S.-Soviet "hotline" goes into operation”, This day in History, http://www.history.com/this-day-in-history/the-us-soviet-hot-line-goes-into-operation
4. The Learning Network, “Aug. 30, 1963 | Communications ‘Hotline’ Connects Soviet and U.S. Heads of State”, The New York Times, Aug.30, 2011 http://learning.blogs.nytimes.com/2011/08/30/aug-30-1963-communications-hot-line-connects-soviet-and-u-s-heads-of-state/
8. The Learning Network, “Aug. 30, 1963 | Communications ‘Hotline’ Connects Soviet and U.S. Heads of State”, The New York Times, Aug.30, 2011 http://learning.blogs.nytimes.com/2011/08/30/aug-30-1963-communications-hot-line-connects-soviet-and-u-s-heads-of-state/
9. Liao Xin, “New Relations Between China and Russia,” Beijing Review in English (FBIS-CHI-97-363, December 1997), 7-8. Grigoriy Arslanov, “Russia: Hotline for Russia’s Yeltsin’s Jiang Now Operational,” Moscow ITAR-TASS in English (FBIS-SOV-98-125, 5 May 98). From “Military Confidence-Building Measures Across the Taiwan Strait" by Kenneth W.Allen. http://www.stimson.org/images/uploads/research-pdfs/cbmapstraits.pdf
10. Hogg Ch. Army phone links China and Russia. BBC News, Beijing. December 29, 2008 http://news.bbc.co.uk/2/hi/asia-pacific/7803028.stm
11. Liao Xin, “New Relations Between China and Russia,” Beijing Review in English (FBIS-CHI-97-363, December 1997), 7-8. Grigoriy Arslanov, “Russia: Hotline for Russia’s Yeltsin’s Jiang Now Operational,” Moscow ITAR-TASS in English (FBIS-SOV-98-125, 5 May 98). From “Military Confidence-Building Measures Across the Taiwan Strait" by Kenneth W.Allen. http://www.stimson.org/images/uploads/research-pdfs/cbmapstraits.pdf
12. India and Pakistan set up hotline. BBC News. 20 June, 2004 http://news.bbc.co.uk/2/hi/south_asia/3822751.stm
13. Choi He-suk. Seoul, Beijing to set up defense hotline. The Korea Herald. http://www.asianewsnet.net/home/news.php?sec=1&id=34296
14. India, China set up hotline to ease border dispute. By Mian Ridge. The Christian Science Monitor. April 8, 2010 http://www.csmonitor.com/World/2010/0408/India-China-set-up-hotline-to-ease-border-dispute
15. The voice of Vietnam. Hotline set up between Chinese, Vietnamese foreign ministries. Feb. 3, 2012 http://english.vov.vn/Home/Hotline-set-up-between-Chinese-Vietnamese-foreign-ministries/20123/135342.vov