Signals intelligence in modern history SIGINT is a contraction of SIGnals INTelligence . Before the development of radar and other electronics techniques , signals intelligence and communications intelligence ( COMINT ) were essentially synonymous . Sir Francis Walsingham ran a postal interception bureau with some cryptanalytic capability during the reign of Elizabeth I , but the technology was only slightly less advanced than men with shotguns , during World War I , who jammed pigeon post communications and intercepted the messages carried . Flag signals were sometimes intercepted , and efforts to impede them made the occupation of the signaller one of the most dangerous on the battlefield . The middle 19th century rise of the telegraph allowed more scope for interception and spoofing of signals , as shown at Chancellorsville . Signals intelligence became far more central to military ( and to some extent diplomatic ) intelligence generally with the mechanization of armies , development of blitzkrieg tactics , use of submarine and commerce raiders warfare , and the development of practicable radio communications . Even Measurement and Signature Intelligence ( MASINT ) preceded electronic intelligence ( ELINT ) , with sound ranging techniques for artillery location . SIGINT is the analysis of intentional signals for both communications and non - communications ( e . g . , radar ) systems , while MASINT is the analysis of unintentional information , including , but not limited to , the electromagnetic signals that are the main interest in SIGINT . World War I . Radio communications were fairly new at this time . At the strategic level , nations gained access to commercial undersea communication cable traffic . Tactically , wired telephones were in wide use , and techniques of intercepting them through ground returns were developed . These intercept techniques have had a resurgence in later wars , where radio was less available or impractical . On the declaration of war , one of Britain ' s first acts was to cut German undersea cables , forcing them to use radio , which the British could intercept . The destruction of more secure wired communications , to improve the intelligence take , has been a regular practice since then . While one side may be able to jam the other ' s radio communications , the intelligence value of poorly secured radio may be so high that there is a deliberate decision not to interfere with enemy transmissions . Russia , when preparing for the Russo - Japanese War in 1904 , had established a tradition of poor communications that would last well after the fall of the Romanovs . The success of this and related salvage and rescue work persuaded the Russian Navy to install wireless sets on many of its ships . In early 1904 , the Russian fleet prepared for war with Japan . The British almost immediately began to intercept their communications , with the complaint “ An intelligence report on signals intercepted by HMS Diana at Suez shows that the rate of working was extremely slow by British standards , while the Royal Navy interpreters were particularly critical of the poor standard of grammar and spelling among the Russian operators . ” After such an embarrassing start , the great Russian mathematical tradition , and probably the national passion for chess , has made Russia , regardless of other shortages , a great innovator in communications and cryptology . Failure to properly protect its communications fatally compromised the Russian Army in its advance early in World War I and led to their disastrous defeat by the Germans under Ludendorff and Hindenburg at the Battle of Tannenberg . Similarly , the interception and decryption of the Zimmerman telegram was an important factor in the US decision to enter the War . Radio researchers at the British Marconi Company realized that strange signals they were receiving were German naval communications , and brought them to the Admiralty . Soon , the British were operating a network of listening posts called " Y - stations " , with Admiralty Room 40 doing the traffic analysis and cryptanalysis . In World War II , the British referred to their traffic analysis function as the " Y service " . In contrast , battles have been lost , or not fought , when senior commanders asked the traffic analysts and direction finder s the wrong question . In World War I , someone at the admiralty knew a little too much detail about SIGINT without fully understanding it . He asked the analysts where call sign " DK " was located , which was that used by the German commander when in harbour . The analysts answered his question precisely , telling him that it was " in the Jade River " . Unfortunately the High Seas Fleet commander used a different identifier " when at sea " , going so far as to transfer the same wireless operator ashore so the messages from the harbour would sound the same . The misinformation was passed to Jellicoe commanding the British fleet , who acted accordingly and proceeded at a slower speed to preserve fuel . The battle of Jutland was eventually fought but its lateness in the day allowed the enemy to escape . Jellicoe ' s faith in cryptographic intelligence was also shaken by a decrypted report that placed the German cruiser SMS Regensburg near him , during the Battle of Jutland . It turned out that the navigator on the Ravensburg was off by in his position calculation . During Jutland , there was limited use of direction finding on fleet vessels , but most information came from shore stations . A whole string of messages were intercepted during the night indicating with high reliability how the German fleet intended to make good its escape , but the brief summary which was passed to Jellicoe failed to convince him of its accuracy in light of the other failures during the day . France had significant signals intelligence in World War I . While the key intelligence achievement in blunting the German drive on Paris in June 1918 was the cryptanalysis of Georges Painvin , had French intercept personnel not captured the message in the ADFGVX cipher , there would have been nothing to cryptanalyze . Between the World Wars . There was substantial SIGINT work between the World Wars , although the secrecy surrounding it was extreme . While it was primarily COMINT , ELINT emerged with the development of radar . Both sides developed direction - finding ( DF ) and communications interception stations during the war , although those programs often began with naval search & rescue . Canada . Canada ' s first signals intelligence intercept site , Special Wireless Station # 1 , was built in 1939 , in Ottawa . " # 2 SWS was located at Grande Prairie , Alberta and # 3 SWS at Victoria , British Columbia . Victoria also had a remote high - frequency direction finding ( HF / DF ) site in Nanaimo approximately to the northwest . " 1 Canadian Special Wireless Group ( 1CSWG ) deployed to Australia in January 1945 . Germany . By the mid - twenties , German Military Intelligence Abwehr was intercepting and cryptanalyzing diplomatic traffic . Under Hermann Göring , the Nazi Research Bureau ( " Forschungsamt " or “ FA ” ) had units for intercepting domestic and international communications . The FA was penetrated by a French spy after 193 ? ? ? ? , but the traffic grew to a point that it could not easily be forwarded . In addition to intercept stations in Germany , the FA established an intercept station in Berne , Switzerland . It penetrated most cryptosystems other than the UK and US . German Condor Legion personnel in the Spanish Civil War ran COMINT against their opponents . United Kingdom . After the First World War , British Army and Navy COMINT merged and formed a new organization , reporting to the Admiralty , called the " Government Code and Cypher School ( GC & CS ) " , with Alastair Denniston as its first head . While it was operational in 1919 , it was realized most of its current work was diplomatic , so it was transferred to report to the Foreign Office . Both GC & CS and the Secret Intelligence Service reported to Hugh Sinclair , in London . In May 1927 , Prime Minister Stanley Baldwin made public some GC & CS solutions of Soviet intercepted message , causing a massive Soviet cryptographic change . By 1940 , GC & CS was working on the diplomatic codes and ciphers of 26 countries , tackling over 150 diplomatic cryptosystems . United States . Naval direction finding and message interception . US communications monitoring of naval signals started in 1918 , and continued , but was used first as an aid to naval and merchant navigation . In October 1918 , just before the end of the war , the US Navy installed its first DF installation at its station at Bar Harbor , Maine , soon joined by five other Atlantic coast stations , and then a second group of 14 installations . These stations , after the end of World War II , were not used immediately for intelligence . While there were 52 Navy medium wave ( MF ) DF stations in 1924 , most of them had deteriorated . The Navy transferred , in July 1941 , the remaining stations to the US Coast Guard . As tension with the Japanese grew , the COMINT situation was being reviewed . In the early 1930s , the Navy started implementing high frequency DF ( HF / DF ) . Eleven locations were planned , primarily on the Atlantic Coast , and beginning with Bar Harbor , Maine , early 1936 . The first operational intercept came from what would later be called Station CAST , at Cavite in the Philippines . There were still technical problems , a development program started , and the first advanced station created at Winter Harbor . In July 1939 , the function turned from training and R & D to operations , and the Navy officially established a Strategic Tracking Organization under a Direction Finder Policy . By December 1940 , the Navy ' s communication organization , OP - 20 - G , had used HF / DF on German surface vessels and submarines . Training continued and cooperation with the British began . In April 1941 , the British gave the US Navy a sample of their best HF / DF set from Marconi . All remaining navigational DF stations were transferred to the Coast Guard in May 1941 , and the Navy concentrated its efforts on COMINT , reporting to OP - 20 - G under Commander Laurance F . Safford . By December 1941 , the Navy established a strategic HF / DF and intercept station , with Atlantic , Pacific and West Coast net control stations managing 20 sites . Increasingly , new site selection emphasized COMINT value over HF / DF . The prototype intercept station had been in Maine , initially in Bar Harbor but relocated to Winter Harbor in 1935 . It principally intercepted European traffic to Tokyo , but also had a section intercepting Soviet traffic . Intercept reorganization came during the first week of September , with Atlantic stations reemphasizing HF / DF , and interception at Jupiter , Florida and Cheltenham , MD . The Cheltenham station was replaced by Chatham MA as the primary intercept station . Beginning in 1937 , US naval ships started intercepting communications , beginning with the destroyer USS Hatfield ( D - 231 ) . It anchored at La Rochelle - Paris and started operating , but lack of intercept training quickly became evident . The Director of Naval Communications established policies and procedures ; it should be noted that COMINT reported Communications , not Intelligence . The European squadron , 40 - T , with USS Raleigh ( CL - 7 ) as flagship , originally was assigned to evacuate civilians from the Spanish Civil War , but a secondary COMINT duty became evident , with a unit established on the USS Omaha ( CL - 4 ) in 1938 , soon designated as Station F , intercepting German , and Italian traffic , later in the Mediterranean . Station F moved to the new flagship , USS Trenton ( CL - 11 ) in June 1939 . They noted significant communications changes two days before the German invasion of Poland , and the intelligence significance was noted and forwarded to Washington . In 1939 , the Atlantic was the priority , with a very short belief Japan was not a threat . In 1940 , formal liaison began with the British , under the terms of a highly secret policy accepted in 1937 . The Special Naval Observer in London was the point of contact , and formal COMINT exchange began in November 1940 . Station F , still on ships , concentrated on Italian traffic in 1940 . OP - 20 - G began cryptanalytic work in July 1940 . OP - 20 - G was acutely aware of British ship losses in the Battle of the Atlantic . Focus remained on the Atlantic , with Agnes Driscoll , the chief cryptanalyst under Lieutenant Lee W . Parke , worked on Italian systems ; German system remained secure . In 1941 , the sensitivity of COMINT increased when the US gave Britain a Purple cipher machine . The British provided technical information on Cryptanalysis of the Enigma as well as current British HF / DF procedures but not , at this stage , the full derived Ultra intelligence . Operational priority increased when Winter Harbor and Amagansett received teleprinter messages for faster relay of intercepts to the analysts in Washington . While the emphasis was now on Japanese traffic , other traffic of interest was still studied . COMINT against the inter - war Japanese . COMINT of Japanese traffic proved invaluable to the Allies at the Washington Naval Conference in 1921 , through cryptanalysis by Herbert Yardley . Then - Secretary of War Henry L . Stimson closed the US Cipher Bureau with the words " Gentlemen do not read each other ' s mail . " Luckily for US COMINT , the Army offered a home to William Friedman after Stimson closed the Yardley operation . Friedman ' s team had four analysts that would become bright figures in American cryptology : Solomon Kullback , Frank Rowlett , and Abraham Sinkov . Kahn ' s memorable comment " If Yardley was the star of American cryptology , Friedman was the Sun " remains apt . They developed largely manual cylindrical and strip ciphers , but , as a result of Friedman ' s advances in cryptanalysis , machine ciphers became a priority , such as the M134 , also known as the SIGABA . While the SIGABA was a rotor machine like the German Enigma machine , it was never known to be cracked . It was replaced by electronic encryption devices . SIS , in contrast with Yardley ' s dependence on cable companies , set up its own radio intercept organization . Eventually , the training and intercept functions were separated for both administrative and security reasons , when , a centralized signals intelligence unit , the 2d Signal Service Company , was set up at Fort Monmouth on 1 January 1939 to control all Signal Corps personnel at the permanent monitoring installations . In this period , SIS paid less attention to tactical SIGINT . World War II . A true world war , SIGINT still tended to be separate in the various theaters . Communications security , on the part of the Allies , was more centralized . Given that there were three major Axis powers , each primarily operating in a subset of the theaters , it is convenient to look at SIGINT from a primarily theater standpoint . From the Allied perspective , the critical theater - level perspectives were the Ultra SIGINT against the Germans in the European theater ( including the Battle of the Atlantic , the Mediterranean Theater of Operations , and MAGIC against the Japanese in the Pacific Theater and the China - Burma - India theater . Germany enjoyed some SIGINT success against the Allies , especially with the Merchant Code and , early in the war , reading American attaché traffic . Japan was the least effective of the major powers in SIGINT . In addition to the official Allies and Axis battle of signals , there was a growing interest in Soviet espionage communications , which continued after the war . British strategic stations were located at places including Darwin , Australia , and a Russian site . Major postwar stations include RAF Menwith Hill and Cyprus . Allied European Theater . The use of SIGINT had even greater implications during World War II . The combined effort of intercepts and cryptanalysis for the whole of the British forces in World War II came under the code name " Ultra " managed from Government Code and Cypher School at Bletchley Park . By 1943 , such was the extent of penetration of Axis communications and the speed and efficiency of distribution of the resulting intelligence , messages sometimes reached allied commanders in the field before their intended recipients . This advantage failed only when the German ground forces retreated within their own borders and they began using secure landline communications . For this reason , the " Battle of the Bulge " took the allies completely by surprise . British Secret Intelligence Service . Initially targeting German spies in Britain , the " Radio Security Service " was soon intercepting a network of German Secret Service transmissions across Europe . Successful decryption was achieved at an early stage with the help of codes obtained from the British XX ( Double Cross ) programme that " turned " German Agents . The combination of double agents and extensive penetration of German intelligence transmissions facilitated a series of highly successful strategic deception programmes throughout WW2 . Royal Navy . Early on , Admiralty dismissal of SIGINT information ( also traffic analysis in this instance ) contributed to the loss of HMS " Glorious " in 1940 . Perhaps the most important role SIGINT played for the Royal Navy , and the merchant ships it protected , was in the Battle of the Atlantic . By comparison with the close and garrulous radio communication between the U - boat submarine high command , BdU , and German submarines in the Atlantic , US submarines in the Pacific were as free as fish . While Ultra cryptanalysis certainly played a role in dealing with German submarines , HF / DF and traffic analysis were complementary . It is unclear why the German submarine command believed that frequent radio communications were not a hazard to their boats , although they seemed confident in the security of their Enigma ciphers , both in the initial three - rotor and subsequent four - rotor versions ( known as Triton to the Germans and Shark to the Allies ) . There was an apparent , mutually reinforcing belief that wolfpack attacks by groups of submarines were much more deadly than individual operations , and confidence the communications were secure . Arguably , the Germans underestimated HF / DF even more than they did British cryptanalysis . Apparently , the Germans did not realize that the Allies were not limited to slow , manually operated direction finders , and also underestimated the number of direction finders at sea . Battle of Britain . ELINT and electronic warfare became critical parts of the Battle of Britain . R . V . Jones was a key scientist in the " Battle of the Beams " , defeating Nazi radio navigation systems ( e . g . , Knickebein ) . While the Ultra COMINT successes against the Germans were not declassified until 1975 , Winston Churchill paid homage to electronic warfare , and its companion ELINT , in his series on the Second World War : In modern terms , MASINT was as important as SIGINT in defeating Nazi navigational systems , with radar control of the defenses a key part of the Battle of Britain . French Resistance and Free French . France consolidated a number of general intelligence and SIGINT units in World War II , producing the wartime Directorate of Studies and Research ( DGER ) by November 1944 . As the Cold War heated , France was concerned with the presence of Communist networks among these units , so , in 1946 , created the External Documentation and Counterespionage Service ( SDECE ) subordinated to the prime minister . Efforts at US coordination during World War II . During the Second World War , the US Army and US Navy ran independent SIGINT organizations , with limited coordination , first on a pure personal basis , and then through committees . Perhaps the strongest outside effect , prior to and during WWII , was the United States Department of State and the White House , the only consumers of intelligence outside the military , especially since both the Army and Navy wanted to have the prestige of providing them with diplomatic COMINT . Note that while the Office of Strategic Services was a fairly autonomous WWII agency , it still , technically , reported to the Joint Chiefs of Staff and received COMINT through military channels . During the war , the military departments became concerned with the creation of new cryptanalytic units in the US government , including the Federal Bureau of Investigation ( FBI ) , Federal Communications Commission ( FCC ) and Department of State . The military finally formalized the sharing of targets in 1944 , but that did not cover the non - military organizations . They established a Joint Army - Navy Radio Intelligence Coordinating Committee , which soon changed its name to the Joint Army - Navy Communications Intelligence Coordinating Committee . US Army . After the Normandy landings , Army SIGINT units accompanied major units , with traffic analysis as or more important than the tightly compartmented cryptanalytic information . Bradley ' s Army Group , created on August 1 , 1944 , had SIGINT including access to Ultra . Patton ' s subordinate Third Army had a double - sized Signal Radio Intelligence Company attached to his headquarters , and two regular companies were assigned to the XV and VIII Corps . The 3250th Signal Service Company , attached to V Corps , moved 10 times in June and July 1944 , and suffered nearly 20 percent casualties during the Battle of the Bulge , including four killed in action . US Navy . In World War II anti - submarine warfare ( ASW ) , shore or ship - based SIGINT often vectored long - range patrol aircraft to U - boats , which they might detect visually or by airborne radar if the submarine was surfaced , or by early sonobuoys used from 1944 on , which could cue dropping depth charges or very early homing torpedoes . The Army demonstrated feasibility of the AN / CRT - 1 sonobuoy , and , by 1944 , the Navy had ordered almost 60 , 000 A daring US Navy feat that received very mixed reviews was the capture of the by Captain Daniel Gallery ' s escort carrier group . While useful cryptomaterial was taken from the boat , Gallery and his immediate chain of command were unaware of the Ultra successes against German submarines . There was considerable concern at Bletchley Park that if the Germans realized a U - boat , and presumably its Enigma had been captured , the Germans might change cryptosystems . The notoriously hot - tempered Chief of Naval Operations , FADM Ernest J . King considered court - martialing Gallery , but relented and authorized the award of a Distinguished Service Medal with a classified citation . Gallery and others had been ordered to not capture any German warships at that particular time , just before the invasion of Normandy lest the resulting change of cryptosystems leave the Allies blind . This was the first time since the War of 1812 between Great Britain and the United States that the United States had captured an enemy ship in wartime . To keep Germany ignorant of the capture of the U - 505 , the submarine was towed to Bermuda . Appropriately , however , the first US sailor , Lieutenant Albert David , to go down the hatch of the submarine , which might have scuttling charges about to detonate or have water rushing in , received the Medal of Honor . The two sailors behind him received the Navy Cross . Axis European Theater . The entire Nazi system suffered from Hitler ' s deliberate fragmenting of authority , with Party , State , and military organizations competing for power , with only Hitler really pulling the strings . Hermann Göring also sought power for its own sake , but was much less effective as the war went on and he became more focused on personal status and pleasure . German air intelligence , during the Battle of Britain , suffered from the structural problem that subordinated intelligence to operations . Operations officers often made conclusions that best fit their plans , rather than fitting conclusions to information . In contrast , British air intelligence was systematic , from the highest - level , most sensitive Ultra to significant intelligence product from traffic analysis and cryptanalysis of low - level systems . Fortunately for the British , German aircraft communications discipline was poor , and the Germans rarely changed call signs , allowing the British to draw accurate inferences about the air order of battle . A 1939 German intelligence study discounted British radar and ground - controlled interception , and believed the only serious defenses were in the London area . Göring was not receptive to dissenting views that key targets were out of bomber range , and significantly out of the range of escort fighters . Allied Pacific Theaters . Several theaters were involved in this part of World War II : CINCPAC / CINCPOA , CINCSWPAC , CINCCBI . Allied cooperation in the Pacific Theater included the joint RAN / USN Fleet Radio Unit , Melbourne ( FRUMEL ) , and the Central Bureau which was attached to the HQ of the Allied Commander of the South - West Pacific area . Australian Army . After consultations between Australian and US signal and communications senior staff , MacArthur ordered Central Bureau to be created , partially to avoid his being dependent on Navy SIGINT . Central Bureau was made up of : At first , Central Bureau was made up of 50 % American , 25 % Australian Army and 25 % Royal Australian Air Force ( RAAF ) personnel , but additional Australian staff joined . In addition , RAAF operators , trained in Townsville , Queensland in intercepting Japanese telegraphic katakana were integrated into the new Central Bureau . Other components of Central Bureau included : Central Bureau broke into two significant Japanese Army cryptosystems in mid - 1943 . Royal Australian Navy . FRUMEL was the joint US - Australian naval SIGINT unit . Commander , later Captain , Eric Nave did not stay long with FRUMEL , which was put under U . S . Navy control in mid - 1942 . He was sent to Central Bureau in mid - 1942 , but it has been suggested he dealt only with lesser Japanese systems , although he had both Japanese language skill and experience with their cryptosystems . The major systems were the target of US Col . Abraham Sinkov . Until Central Bureau received replacement data processing equipment for that which was lost in the Philippines , as of January 1942 , U . S . Navy stations in Hawaii ( Hypo ) , Corregidor ( Cast ) and OP - 20 - G ( Washington ) decrypted Japanese traffic well before the U . S . Army or Central Bureau in Australia . Cast , of course , closed with the evacuation of SIGINT personnel from the Philippines . US Navy . US strategic stations targeted against Japanese sources included Station HYPO in Hawaii , Station CAST in the Philippines , station BAKER on Guam , and other locations including Puget Sound , and Bainbridge Island . US COMINT recognized the growing threat before the Pearl Harbor attack , but a series of errors , as well as priorities that were incorrect in hindsight , prevented any operational preparation against the attack . Nevertheless , that attack gave much higher priority to COMINT , both in Washington DC and at the Pacific Fleet Headquarters in Honolulu . Organizational tuning corrected many prewar competitions between the Army and Navy . Perhaps most dramatically , intercepts of Japanese naval communications yielded information that gave Admiral Nimitz the upper hand in the ambush that resulted in the Japanese Navy ' s defeat at the Battle of Midway , six months after the Pearl Harbor attack . US Army . The US Army had shared , with the Navy , the Purple attack on Japanese diplomatic cryptosystems . Many histories assume Purple included Japanese military cryptanalysis , but those were separate projects , although generally under the same organizations . After creation of the Army Signal Security Agency , the cryptographic school at Vint Hill Farms Station , Warrenton , Virginia , trained analysts . As a real - world training exercise , the new analysts first solved the message center identifier system for the Japanese Army . Until Japanese Army cryptosystems were broken later in 1943 , the order of battle and movement information on the Japanese came purely from direction finding and traffic analysis . Traffic analysts began tracking Japanese units in near real time . A critical result was the identification of the movement , by sea , of two Japanese infantry divisions from Shanghai to New Guinea . Their convoy was intercepted by US submarines , causing almost complete destruction of these units . Army units in the Pacific included the US 978th Signal Company based at the Allied Intelligence Bureau ' s secret " Camp X " , near Beaudesert , Queensland south of Brisbane . This unit was a key part of operations behind Japanese lines , including communicating with guerillas and the Coastwatcher organization . It also sent radio operators to the guerillas , and then moved with the forces invading the Philippines . US Army Air Force . Even as the planes burned at Clark Field , hours after the Pearl Harbor attack , Lieutenant Howard Brown , of the 2nd Signal Service Company in Manila , ordered the unit to change its intercept targeting from Japanese diplomatic to air force communications . The unit soon was analyzing Japanese tactical networks and developing order of battle intelligence . He moved from Manila to Corregidor on Christmas Eve . They learned the Japanese air - to - ground network was Sama , Hainan Island , with one station in Indo - China , one station near Hong Kong , and the other 12 unlocated . Two Japanese naval stations were in the Army net , and it handled both operations and ferrying of aircraft for staging new operations . Traffic analysis of still - encrypted traffic helped MacArthur predict Japanese moves as the Fil - American forces retreated in Bataan . Evacuated , as were most SIGINT people , from the Philippines , Brown , helped build the Australian - American intercept station , and 126th Radio Intelligence Company , at Townsville , Queensland . He later trained the Air Force SIGINT staff . US Air Force Far East , and its subordinate 5th Air Force , took control of the 126th in June 1943 . The 126th was eventually placed under operational control of U . S . Air Force Far East in June 1943 to support 5th Air Force . Interception and traffic analysis from the company supported the attack into Dutch New Guinea in 1944 . The US began airborne ELINT against Japanese radar in the Aleutians , using a modified B - 24 aircraft in January 1943 . ELINT was much less significant in the early Pacific War than in the European Theater , probably because strategic bombing using electronic navigation aids was not a critical issue . US Marine Corps . In 1943 , the US Marines organized the 2nd Radio Research Platoon , which was the original unit in a chain of tactical SIGINT units that also made strategic contributions . Japanese SIGINT . Japan had been fighting in China and Manchuria since the 1930s . They were overconfident in their communications security . Indochina . In September 1940 , the Japanese moved into the Haiphong area of French Indochina , claiming they wanted to disrupt supply lines to their war in China . In June 1941 , they expanded their occupation to all of the colony , to which the US responded with embargoes that the Japanese regarded as a " casus belli " for the Battle of Pearl Harbor . US Army and Navy cryptanalysts were able to follow events , initially through their penetration of the RED cryptomachine , and then the Purple system , introduced in 1939 and broken in 1940 . Principally to track shipping , the US monitored Japanese , and eventually French colonial administration , traffic , through WWII . In general , the area was not of strong operational interest to the Allies , except for planning submarine attacks on shipping , and occasional air raids on transportation infrastructure . On the strategic level , however , the US began to learn more about the resistance groups in Indochina . These groups , especially the Viet Minh , fought the Japanese , but would later fight the French administration , and eventually the Republic of Vietnam ( RVN ; South Vietnam ) . In March 1945 , the Japanese , through their own COMINT , were alerted of a potential French coup against the Japanese occupation . Within 48 hours , all the French administrators and troops were captured , except for about 4 , 000 troops who fled into China . September 1945 found an emboldened Viet Minh , under Ho Chi Minh and assisted by a US OSS team under MAJ Archimedes Patti , declare the independence of the Democratic Republic of Vietnam ( DRV ; North Vietnam ) . The Allies , however , did not recognize Ho ' s government , staying loyal to the French . While the French claimed Ho ' s movement was Communist , US State Department analytic reports in 1947 and 1948 , written from all - source intelligence including COMINT , gave no indication that the Vietnamese Communist Party was controlled by Moscow . Western counterespionage . From 1943 to 1980 , the VENONA project , principally a US activity with support from Australia and the UK , recovered information , some tantalizingly only in part , from Soviet espionage traffic . While the Soviets had originally used theoretically unbreakable one - time pad s for the traffic , some of their operations violated communications security rules and reused some of the pads . This reuse caused the vulnerability that was exploited . VENONA gave substantial information on the scope of Soviet espionage against the West , but critics claim some messages have been interpreted incorrectly , or are even false . Part of the problem is that certain persons , even in the encrypted traffic , were identified only by code names such as " Quantum " . Quantum was a source on US nuclear weapons , and is often considered to be Julius Rosenberg . The name , however , could refer to any of a number of spies . Aftermath of World War II and the 1950s . After the end of World War II , all the Western allies began a rapid drawdown . At the end of WWII , the US still had a COMINT organization split between the Army and Navy . Post Cold War . 1980s US Tactical SIGINT policy and doctrine . After the Beirut deployment , the US Marine Corps did an after - action review of the 2nd Radio Battalion detachment that went with that force . Lieutenant General Alfred M . Gray , Jr . then commanding Fleet Marine Force Atlantic , and Lieutenant Colonel Bill Keller , commanding 2nd Radio Battalion , did an after - action review . Part of the reason for this was that the irregular units that presented the greatest threat did not follow conventional military signal operating procedures , and used nonstandard frequencies and callsigns . Without NSA information on these groups , the detachment had to acquire this information from their own resources . Recognizing that national sources simply might not have information on a given environment , or that they might not make it available to warfighters , Lieutenant General Gray directed that a SIGINT function be created that could work with the elite Force Reconnaissance Marines who search out potential enemies . At first , neither the Force Reconnaissance nor Radio Battalion commanders though this was viable , but had orders to follow . Initially , they attached a single Radio Battalion Marine , with an AN / GRR - 8 intercept receiver , to a Force Reconnaissance team during an exercise . A respected Radio Marine , Corporal Kyle O ' Malley was sent to the team , without any guidance for what he was to do . The exercise did not demonstrate that a one - man attachment , not Force Recon qualified , was useful . In 1984 , Captain E . L . Gillespie , assigned to the Joint Special Operations Command , was alerted that he was to report to 2nd Radio Battalion , to develop a concept of operations for integrating SIGINT capabilities with Force Recon , using his joint service experience with special operations . Again , the immediate commanders were not enthusiastic . Nevertheless , a mission statement was drafted : " To conduct limited communications intelligence and specified electronic warfare operations in support of Force Reconnaissance operations during advance force or special operations missions . " It was decided that a 6 - man SIGINT team , with long / short range independent communications and SIGINT / EW equipment , was the minimum practical unit . It was not practical to attach this to the smallest 4 - man Force Recon team . General Gray directed that the unit would be called a Radio Reconnaissance Team ( RRT ) , and that adequate planning and preparation were done for the advance force operations part of the upcoming Exercise Solid Shield - 85 . Two six - man teams would be formed , from Marines assigned from the Radio Battalion , without great enthusiasm for the assignment . One Marine put it " There is nothing that the Marine Corps can do to me that I can ' t take . " From 1986 on , RRTs accompanied MEU ( SOC ) deployments . Their first combat role was in Operation Earnest Will , then Operation Praying Mantis , followed by participation in the 1989 United States invasion of Panama 1990s . Terrorism from foreign groups became an increasingly major concern , as with the 1992 al - Qaeda attack in Yemen , the 1993 truck bombing of the World Trade Center , 1995 ( Saudi communications center ) and 1996 ( Khobar Towers ) in Saudi Arabia , and the 1998 bombings of the US embassies in Dar es Salaam , Tanzania and Nairobi , Kenya . Third world and non - national groups , with modern communications technology , in many ways are a harder SIGINT target than a nation , such as Russia or China , that sends out large amounts of traffic . According to the retired Commandant of the US Marines , Alfred M . Gray , Jr . , some of the significant concerns of these targets are : France . While the Helios satellite was IMINT , not SIGINT , it helped put perspective on program costs . [ Helios 1A was launched on 7 July 1995 . The Cerise ( satellite ) SIGINT technology demonstrator also was launched in 1995 ; it is not clear if it was on the Helios 1 launch . A radio propagation experiment , S80 - T , was launched in 1992 , as a predecessor of the ELINT experiments . Financial pressures in 1994 - 1995 caused France to seek Spanish and Italian cooperation for Helios 1 and German contributions to HELIOS 2 . Helios 2A was launched in 2004 . France , still desiring to have three different space - based intelligence systems ( IMINT , radar surveillance , SIGINT ) , had to face extremely high costs . In 1994 - 1995 , French legislators tried to reduce some of these plans . In response , the French government sought Italian and Spanish funding in , and cooperation with , the HELIOS 1 program . They also sought German involvement in Helios 2 . The HELIOS 2A launch also was accompanied by a small constellation of ELINT satellites . The Cerise satellite ELINT technology demonstrator , also launched in 1995 , was damaged by a collision with another French payload , SPOT - 1 , in the following year . Clementine , the second - generation ELINT technology demonstrator , was launched in 1999 . United Kingdom . Controversy arose over alleged British interception of communications to Ireland from a facility called the Ministry of Defence Electronic Test Facility in a British Nuclear Fuels Limited site at Capenhurst , Cheshire . This facility was in the line of microwave towers from the UK - Ireland 1 cable ( Dublin to Anglesey ) landing to BT in London . Besides the Capenhurst tower , communications to and from the Irish Republic were also intercepted at a similar but A smaller GCHQ station in County Armagh was said to target links between Dublin and Belfast , and a third station intercepted satellite communications in Cornwall . Irish politicians , led by former Prime Minister Albert Reynolds , demanded an investigation . 2000s . As evidenced by the Hainan Island incident , even while China and the US may cooperate on matters of mutual concern towards Russia , the Cold War has not completely disappeared . There was more regional cooperation , often driven by concerns about transnational terrorism . European countries also are finding that by sharing the cost , they can acquire SIGINT , IMINT , and MASINT capabilities independent of the US . In the US , both communications security and COMINT policies have been evolving , some with challenges . The adoption of a Belgian - developed encryption algorithm , approved in a public process , and accepted both for sensitive but unclassified traffic , as well as for classified information sent with NSA - generated and maintained keys , redraws the cryptologic environment as no longer NSA or not - NSA . Controversy continues on various types of COMINT justified as not requiring warrants , under the wartime authority of the President of the United States . Technologically , there was much greater use of UAVs as SIGINT collection platforms . Hainan Island incident . In 2001 , a US EP - 3 SIGINT aircraft collided with a shadowing Chinese fighter , in what became known as the Hainan Island incident . Each side blamed the other ; the US claimed the aircraft was in international airspace . The fighter pilot died , and the EP - 3 made an emergency landing in China , erasing as much sensitive information as possible . While the Chinese released the aircraft several months after releasing the crew , the most sensitive information was not so much the aircraft ' s instrumentation , but the signals it was targeting and the reference material about the Chinese " electronic order of battle " . European Space Systems cooperation . French initiatives , along with French and Russian satellite launching , have led to cooperative continental European arrangements for intelligence sensors in space . In contrast , the UK has reinforced cooperation under the UKUSA agreement . French space - based intelligence . On 18 December 2004 , HELIOS 2A , built by EADS - Astrium for the French Space Agency ( CNES ) , was launched into a Sun - synchronous polar orbit at an altitude of about 680 kilometers . There it will serve the French defense ministry , as well as cooperating European countries . HELIOS 2B is scheduled for launch in 2008 . The same launcher carried French and Spanish scientific satellites and four Essaim ( " Swarm " ) experimental ELINT satellites Sources in the French procurement agency , DGA , confirmed Essaim , a system of ground station and satellite constellation , is working well . There have been French defense complaints about Essaim being a third technology demonstrator , after the 1995 Cerise and 1999 Clementine . DGA countered that Essaim will demonstrate more advanced technology , important to convince other European governments to help with the cost . Essaim is to provide some operational data . The first of three ground stations is operational , with three satellites in operation and the fourth considered an in - orbit spare . In a Ministère de la Défense 18 December 2004 statement , France announced that Helios 2A is part of an exchange program planned with the German SAR Lupe and Italian COSMO - SKYMED systems , under development respectively in Germany and Italy . German Space Systems . Following the first successful launch on December 19 , 2006 , about a year after the intended launch date , further satellites were launched at roughly six - month intervals , and the entire system of this five - satellite SAR Lupe synthetic aperture radar constellation achieved full operational readiness on 22 July 2008 . SAR is usually considered a MASINT sensor , but the significance here is that Germany obtains access to French satellite ELINT . Italian Space Systems . With the first satellite launched on June 8 , 2007 , Italy and France are cooperating on the deployment of the dual - use Orfeo civilian and military satellite system . Orfeo is a dual - use ( civilian and military ) earth observation satellite network developed jointly between France and Italy . Italy is developing the Cosmo - Skymed X - band polarimetric SAR , to fly on two of the satellites . The other two will have complementary French electro - optical payloads . The second Orfeo is scheduled to launch in early 2008 . While this is not an explicit SIGINT system , the French - Italian cooperation may suggest that Italy can get data from the French Essaim ELINT microsatellites . Acceptance of cryptologic expertise outside NSA . The US government withdrew the last approvals for the Data Encryption Standard , approved for unclassified use in 1976 but now considered quite vulnerable . Its replacement , the Advanced Encryption Standard ( AES ) was approved in 2002 . AES , when used with NSA - supplied keys , is approved for TOP SECRET traffic as well as unclassified , and may be considered a reference point for strong commercial encryption . AES appears , at the present time , to be secure when used properly , which represents a major change in US policy about the availability of strong communications security . Not all governments will allow the use of such strong ciphers . That the algorithm chosen came from Europe points to a more multilateral world with respect to communications security . AES was developed by two Belgian cryptographers , Joan Daemen and Vincent Rijmen , and submitted to the AES selection process under the name " Rijndael " , a portmanteau of the names of the inventors . Terrorism and response in the US . As a result of the 9 / 11 attacks , intensification of US intelligence efforts , domestic and foreign , were to be expected . A key question , of course , was whether US intelligence could have prevented or mitigated the attacks , and how it might prevent future attacks . There is a continuing clash between advocates for civil liberties and those who assert that their loss is an agreeable exchange for enhanced safety . SIGINT and the 9 / 11 attacks . In a statement to a joint meeting of the House and Senate Intelligence Committees , NSA Director LTG Michael Hayden said " NSA had no SIGINT suggesting that al - Qa ' ida was specifically targeting New York and Washington , D . C . , or even that it was planning an attack on U . S . soil . Indeed , NSA had no knowledge before September 11 that any of the attackers were in the United States , although the FBI was tailing them . See Able Danger . " We are digging out of a deep hole . NSA downsized about one - third of its manpower and about the same proportion of its budget in the decade of the 1990s . That is the same decade when packetized communications ( the e - communications we have all become familiar with ) surpassed traditional communications . That is the same decade when mobile cell phones increased from 16 million to 741 million an increase of nearly 50 times . That is the same decade when Internet users went from about 4 million to 361 million an increase of over 90 times . Half as many landlines were laid in the last six years of the 1990s as in the whole previous history of the world . In that same decade of the 1990s , international telephone traffic went from 38 billion minutes to over 100 billion . This year , the world ' s population will spend over 180 billion minutes on the phone in international calls alone . " throughout the summer of 2001 we had more than 30 warnings that something was imminent . We dutifully reported these , yet none of these subsequently correlated with terrorist attacks . The concept of " imminent " to our adversaries is relative ; it can mean soon or imply sometime in the future " US domestic surveillance issues . Under the George W . Bush administration , there has been a large - scale and controversial capture and analysis of domestic and international telephone calls , claimed to be targeted against terrorism . It is generally accepted that warrants have not been obtained for this activity , sometimes called Room 641A after a location , in San Francisco , where AT & T provides NSA access . While very little is known about this system , it may be focused more on the signaling channel and Call detail record s than the actual content of conversations . Another possibility is the use of software tools that do high - performance deep packet inspection . According to the marketing VP of Narus , " Narus has little control over how its products are used after they ' re sold . For example , although its lawful - intercept application has a sophisticated system for making sure the surveillance complies with the terms of a warrant , it ' s up to the operator whether to type those terms into the system . . . " That legal eavesdropping application was launched in February 2005 , well after whistle - blower Klein allegedly learned that AT & T was installing Narus boxes in secure , NSA - controlled rooms in switching centers around the country . But that doesn ' t mean the government couldn ' t write its own code to do the dirty work . Narus even offers software - development kits to customers " . The same type of tools with legitimate ISP security applications also have COMINT interception and analysis capability . Former AT & T technician Mark Klein , who revealed AT & T was giving NSA access , said in a statement , said a Narus STA 6400 was in the NSA room to which AT & T allegedly copied traffic . The Narus device was " known to be used particularly by government intelligence agencies because of its ability to sift through large amounts of data looking for preprogrammed targets . "