Aerospace Defense Command Aerospace Defense Command is an inactive United States Air Force Major Command . Established in 1946 under the United States Army Air Force , its mission was to organize and administer the integrated air defense system of the Continental United States ( CONUS ) , exercise direct control of all active measures , and coordinate all passive means of air defense . The command was inactivated on 31 March 1980 . Overview . The mission of air defense is a major foundation of the United States Air Force . In 1916 , Alexander Graham Bell warned about the possibility of airship raids on the United States . For the next 25 years , experts studied the problem of air defense and lay the foundation for the future . The War Department established an " Air Defense Command " as part of the Army Air Corps on 26 February 1940 . This command , operating under the control of the United States First Army Commander from 2 March 1940 , to 9 September 1941 , engaged in planning for air defense of the Continental United States . Before the United States entered World War II , air defense was divided among the four GHQ Air Force districts later , First , Second , Third , and Fourth Air Forces based in the United States . Initially , there was a sizeable effort to defend the country from aerial attack . In mid - 1944 , when the threat of air attack seemed negligible , this air defense organization was disbanded . Subsequently , no real air defense organization existed until the second Air Defense Command was established in 1946 as a major command of the Army Air Forces ( AAF ) . However political issues within the Pentagon were not to be overlooked . There was concern within the Air Force that funds to create an " impenetrable air defense " would be obtained by siphoning money away from Strategic Air Command ' s mission of nuclear deterrence . Apart from the intramural disputes , The Air Force battles with the Army over control of Surface - to - Air missiles and other issues were particularly intense . The initial mission of Air Defense Command was to stop a handful of conventionally armed piston engine - powered bombers on a one - way mission , flying a predictable course . The threat swiftly grew to the prospect of an attack by hundreds of turboprop and jet bombers armed with thermonuclear weapons and attacking from different directions . Meeting such a threat required the creation of a huge system . It consumed billions of dollars . It required leadership , foresight , and brilliant science . In the early 1960s , however , aircraft air defense was overtaken by events , as USAF shifted its emphasis away from intercepting bombers and toward the detection of Intercontinental Ballistic Missiles ( ICBM ) s . Robert S . McNamara , Secretary of Defense in the Kennedy and Johnson Administrations , concluded that the ICBM problem was so overwhelming that it rendered relatively inconsequential the threat of Soviet bomber attack . With the rise of the ICBM , emphasis on air defense against bombers went into a sharp decline . Air Defense Command was redesignated as Aerospace Defense Command ( ADCOM ) in 1968 to reflect that fundamental mission change . The Aerospace Defense Command declined after 1979 when its resources were divided between Tactical Air Command and Strategic Air Command . Under TAC , the Air National Guard and Air Force Reserve gradually assumed more and more of the air defense mission . In 1980 , ADCOM was inactivated . Some functions of the command passed to the Aerospace Defense Center , a direct reporting unit assigned to Headquarters , NORAD that inactivated on 1 October 1986 . Today , ADC ' s proud heritage is maintained by NORAD , Air Combat Command , the Air National Guard , and the Air Force Reserve . History . World War II . Origins . In spite of the outbreak of World War II in Europe during September 1939 , the War Department did not consider air defense of the United States a major concern . This was because military planners did not envisage a large - scale bomber assault on this country if the United States became involved in active combat . Most airmen agreed with General George C . Marshall when he said in May 1940 that the defense of the country could be assured by denying a potential enemy bases in the Western Hemisphere . Nevertheless , on the recommendation of General Henry H . Arnold , the Chief of the United States Army Air Corps , the War Department established an " Air Defense Command " on 26 February 1940 . As a component of the U . S . First Army , its mission was to plan for and execute the air defense of the continental United States . It consisted of personnel from the Air Corps , the Coast Guard and Army Signal Corps . At a conference held in February 1941 , General Marshall assigned the responsibility for air defense to the new continental Air Forces being developed under GHQ Air Force , each of which contained an " Interceptor Command " . The Interceptor Commands were charged with air defense of their areas , but were subject to the overall supervision of four new Numbered Air Forces , which were aligned with the four Army defense areas , which were vested with overall defense responsibility . These districts were : RADAR Development . The development of early warning RADAR ( radio detection and ranging ) technology in the 1930s made effective air defense possible . By December 1936 the Signal Corps successfully tracked an aircraft to a distance of seven miles using short - pulse emission of radio waves . Air Corps representatives saw the value of the device for early warning . Service trials of the first early warning RADAR , the SCR - 270 , were held late in 1939 , with the device being officially adopted in May 1940 . The entry of the United States in World War II resulted in a major expansion of air defense facilities , especially on the two ocean coasts . Ninety - five radar stations were eventually completed : 65 on the Pacific Coast and 30 on the Atlantic , although about 75 was the maximum number operational at any one time . The principal radars ( known as : " Signal Corps Radio " ) in use during the war were the SCR - 270 ( mobile ) and the SCR - 271 ( fixed ) , with ground control intercept radar ( SCR - 588 ) being added during 1943 for close - in coverage ( up to 50 miles ) for tracking and controlling fighters from the ground . Ground observers . The World War II Air Defense Command established a ground observer network in air defense exercises in 1940 - 1941 which greatly facilitated the War Department ' s organization of the AAF Ground Observer Corps in 1942 . The information network grew - during the war to a maximum of 15 information centers along both coasts and four standby centers along the Gulf of Mexico coastline , with a total of 14 , 000 observation posts and an estimated 1 , 500 , 000 civilian volunteers enrolled . Interceptor aircraft . The shortage of fighter planes in the early part of the war proved a serious handicap to the air defense effort . However , the situation improved during 1942 and 1943 with the availability in quantity of the P - 38 Lightning and P - 47 Thunderbolt , which equipped units which were attached to Air Defense Fighter Wings over major cities along the east and west coasts as part of their training for overseas combat duty . Still , until the introduction of the P - 61 Black Widow , the lack of all - weather day / night aircraft made the success of interception at night , or in inclement weather , highly doubtful . The P - 61 however , was not made available for air defense operations in the United States during the war , its need in the overseas combat theaters taking priority . Anti - Aircraft artillery . Anti - aircraft artillery ( AAA ) provided for local defense . AAA underwent drastic changes during the war , with unified AAA commands emerging on both coasts after the Pearl Harbor Attack . After considerable controversy the control of AAA was placed under the Army Air Forces interceptor commands . This elaborate air defense system fortunately never had to deal with a major air attack . Until the Battle of Midway in June 1942 , air defenses remained on a high alert , but after the naval battle , only occasional alerts were called : As the threat decreased , the defenses gradually reduced , with the focus on the four Air Forces in the United States ( Zone of Interior " ZI " ) being the organization and training of combat units and replacement personnel for deployment to overseas theaters . The ADC Air District structure was abolished in April 1944 along with Air Defense Command . The numbered air force s and their training mission was turned over to the USAAF Continental Air Forces training command . The Ground Observer Corps was dissolved , the radar net reduced in size , and the Air Defense Fighter Wings being reduced to administrative units , not equipped or manned . By war ' s end on the east coast three control centers and nine radar stations remained . On the west coast three control centers and 22 radars were active . With demobilization in 1945 , the air defenses of the United States had virtually ceased to exist . Associated units . First Air Force air defense fighter wings : Fourth Air Force air defense fighter wings : Cold War History . The second iteration of Air Defense Command ( ADC ) was established on 21 March 1946 as a component of the United States Army Air Forces . General Carl Spaatz had undertaken a major reorganization of the Army Air Forces after the end of World War II to incorporate many of the lessons learned . His reorganization included the establishment of three new combat commands in the United States : Strategic Air Command ( soon known everywhere as SAC ) , to provide a long - range striking force capable of bombardment operations in any part of the world : Tactical Air Command ( TAC ) , to support the operations of ground forces , and Air Defense Command ( ADC ) , to provide for the air defense of the United States . Postwar era . Air Defense Command was constituted on 21 March 1946 , and was activated and headquartered at Mitchel Field , New York , on 27 March 1946 . It assumed control of the 414th Night Fighter Squadron , which was an un - manned and un - equipped administrative organization , and the 425th Night Fighter Squadron , which was manned by one officer and two enlisted men . Two bases , Mitchel Field , New York and Hamilton Field , California , were assigned to ADC . Two numbered air forces , the First Air Force ( Mitchel ) and Fourth Air Force ( Hamilton ) were allocated . Shortly afterwards , on 10 June , the ADC mission was expanded to the extent that ADC was required to coordinate within the United States the means available from other services for air defense , such as Naval and Marine aircraft units temporarily shore - based . In 1947 , the 505th Aircraft Control and Warning Group , the first postwar aircraft control and warning organization , was activated at McChord Field , Washington on 21 May . The newly established United States Air Force granted ADC the authority to use the fighter and radar forces of SAC , TAC and the Air National Guard in the event of a national emergency . Most air defense units at the time were part of the Air National Guard . Four additional numbered air forces , the Second ( Fort Crook , Nebraska ) ; Tenth ( Brooks Field , Texas ) ; Eleventh ( Olmstead Field , Pennsylvania ) , and the Fourteenth Air Force ( Orlando Air Base , Florida ) were assigned . ( Eleventh Air Force was inactivated on 1 July 1948 . It has no relationship to the current or previous 11th Air Force ) . At the end of World War II a number of factors operated to belittle the need for elaborate air defenses . The result was that the construction of a modern air defense system lagged . However , with the Cold War breaking out between the United States and the Soviet Union in 1948 , a more urgent note was struck in air defense . Radars were removed from storage and deployed along the Atlantic and Pacific coasts . ADC activated two Divisions , the 25th Air Division at Silver Lake Air Warning Station , Washington on 25 October 1948 and the 26th Air Division at Roslyn Air Warning Station , New York 16 November . Both of these organizations were active for over 40 years in the air defense of the United States , being inactivated after the end of the Cold War . Their successor organizations became the current Eastern ( EADS ) and Western Air Defense Sector ( WADS ) of today ' s Continental United States NORAD Region ( CONR ) . Continental Air Command . On 1 December 1948 Continental Air Command ( ConAC ) was created and given the mission of air defense . Both ADC and Tactical Air Command were reduced to operating agencies under ConAC which consisted of a small staff of planners . TAC fighter units while in the United States assumed an air defense mission which augmented the meager resources of ADC . In March 1949 , the six numbered air forces inherited from ADC were relieved of their air defense responsibilities . Two new units , the Eastern and Western Air Defense Liaison Groups were created in their place . In September , these provisional units were re - designated as the Eastern Air Defense Force and Western Air Defense Force , under which all atmospheric air defense units ( Radar and Interceptor ) were placed , divided by the 103rd meridian west . During 1949 and early 1950 , steady strides were made in air defense . In March 1949 , Congress authorized the construction of a " permanent " radar system along the coasts and land borders of the United States . Following the explosion of a nuclear weapon by the Soviet Union in August 1949 , the Air Force issued requirements for an operational air defense system by 1952 , and the building of the permanent radar network was accelerated . Air Defense Command . The outbreak of the Korean War in June 1950 underlined the need for increased air defense precautions . In addition , the perceived threat of an airborne atomic attack by the Soviet Union with its Tu - 4 copy of the B - 29 or Tu - 95 strategic bomber force led to the separation of Air Defense Command from ConAC , and its re - establishment as an Air Force major command to counter the perceived Soviet threat . Air Defense Command was officially re - established as a major air command on 1 January 1951 at Mitchel AFB , New York . The command headquarters was moved to Ent AFB , Colorado on 8 January 1951 . ConAC transferred to ADC 21 active - duty fighter squadrons and 37 Air National Guard fighter squadrons operationally gained by ADC if activated . It was also assigned the 25th , 26th 27th and 28th Air Divisions ( Defense ) With the reestablishment ADC as a major command ( as well as TAC ) , ConAC ' s mission became one of administering the Air Force Reserve . Early warning Radars . Early - warning radars are a fundamental necessity of the United States air defense system . As the Soviet Cold War threat became generally recognized , so did a requirement for adequate early warning . In the earliest effort to provide it , the USAF came up with a system in 1947 known as " Radar Fence Plan , " which called for 411 radar stations and 18 control centers and was projected to cost $ 600 million . The cost of the plan clearly exceeded the Air Force ability to pay , and planners tried to develop a less expensive version . The answer was something that became known as the " Permanent System . " It was to consist of 85 radar stations and 11 control centers , in the United States and Alaska . The cost was estimated to be about $ 116 million , spread over the period 1949 - 50 . It became fully operational in April 1953 . However , the Air Force was loath to ignore the immediate threat , and it built a temporary system , sarcastically but aptly called " Lashup . " It comprised 43 sites by 1950 . The system used World War II AN / CPS - 5 search radar systems that were deficient in range and in low - altitude detection capability . In addition , 36 Air National Guard fighter units were called to active duty for the mission . Lashup had the great value of introducing the US again to the concept of a radar air defense system . ADC was reinstated as a full major command in January 1951 , and ADC headquarters established at Ent AFB , Colorado . By 1953 , a modern United States continental system of Ground Control Interception ( GGI ) Radar stations had been completed and additional radar units were programmed to blanket the country with medium and high - altitude radar cover . Domestically the gaps were filled by additional Federal Aviation Administration ( FAA ) radar stations and the organization of a million American men and women into the Ground Observer Corps ( GOC ) which served the nation until it was disbanded in 1959 . Work was begun in 1953 to erect a number of off - shore radars platforms bristling with radar equipment and embedded in the ocean bed known as Texas Towers to extend the range of RADAR into the Atlantic Ocean to cover the northern approach routes far out to sea . One of the Texas Towers ( TT - 4 ) collapsed into the Atlantic Ocean with significant loss of life in January 1961 . The tragedy of TT - 4 , as much as anything else , sealed the fate of the others . While both remaining towers were immediately checked for safety and structural strength , and pronounced sound in this regard , their days were numbered . The entire project was ended in 1963 , and the remaining facilities were decommissioned and sunk in 1964 . During the mid - 1950s , the nation ' s defense planners devised the idea of extending the wall of powerful land - based radar seaward with Airborne early warning and control units . This was done by equipping two wings of Lockheed RC - 121 Warning Star aircraft , the 551st Airborne Early Warning and Control Wing , based at Otis Air Force Base , Massachusetts , and the 552nd AEWCW , based at McClellan Air Force Base , California , one wing stationed on each coast . The RC - 121s , EC - 121 s and Texas Towers , it was believed , would contribute to extending contiguous east - coast radar coverage some 300 to 500 miles seaward . In terms of the air threat of the 1950s , this meant a gain of at least 30 extra minutes warning time of an oncoming bomber attack . As the USAF prepared to deploy the Tactical Air Command E - 3 Sentry in the later 1970s , active - duty units were phased out EC - 121 operations by the end of 1975 . All remaining EC - 121s were transferred to the Air Force Reserve , which formed the 79th AEWCS at Homestead Air Force Base , Florida in early 1976 . The active duty force continued to provide personnel to operate the EC - 121s on a 24 - hour basis , assigning Detachment 1 , 20th Air Defense Squadron to Homestead AFB as associate active duty crews to fly the Reserve - owned aircraft . Besides monitoring Cuban waters , these last Warning Stars also operated from NAS Keflavik , Iceland . Final EC - 121 operations ended in September 1978 . Interceptor Aircraft . The growth and development of the ADC air defense system grew steadily throughout the Cold War era . From four day - type fighter squadrons ( FDS ) in 1946 , the ADC interceptor force grew to ninety - three ( 93 ) active Air Force fighter interceptor squadrons , seventy - six ( 76 ) Air National Guard fighter interceptor squadrons , several Naval fighter squadrons , USAF and USN airborne early warning squadrons , radar squadrons , training squadrons and numerous support units that have played important roles in our nation ' s defense . When the Cold War began , bomber technology was ascendant and would continue to be so for more than a decade . The first ADC interceptor , the P - 61 Black Widow did not have the capabilities to engage the Soviet Tu - 4 bomber . Its successor , the F - 82 Twin Mustang , was even more disappointing . It took a long time to get into production and did not perform well in inclement weather . The early jet fighters , such as the F - 80 Shooting Star and F - 84 Thunderjet , lacked all - weather capability and were deemed useless for air defense purposes . Much hope was placed on two jet - powered interceptors , the XP - 87 Blackhawk and the XP - 89 Scorpion . ( Designations changed to XF - 87 and XF - 89 . ) They , in their turn , proved to be inadequate . The XF - 87 was cancelled and the Scorpion had to undergo extensive redesign . The first - generation jets gave way to all - weather dedicated interceptor jets . The F - 94 Starfire was pressed into service as an " interim " interceptor . North American in 1949 pushed an interceptor version of the Sabre , the F - 86D . Despite the demands its complexity made upon a single pilot , the F - 86D was backed by senior Air Force officials . Some 2 , 504 would be built and it would in time be the most numerous interceptor in the Air Defense Command fleet , with more than 1 , 000 in service by the end of 1955 The F - 86D was not ideal , however , for its afterburner consumed a great deal of fuel in getting it to altitude , and the pilot was overburdened by cockpit tasks . The F - 89D was modified to accept AIM - 4 Falcon guided missiles ( F - 89H ) and AIR - 2 Genie atomic warhead rockets ( F - 89J ) as armament . The F - 86D was modified ( F - 86L ) to include the SAGE data link , thereby permitting more precise automatic control from the ground . The F - 86L and F - 89H became available in 1956 , the F - 89J in 1957 . Even more advanced were the Century Series supersonic interceptors . First was the F - 102A Delta Dagger , which appeared in 1956 . The F - 104A Starfighter came along in 1958 . The F - 101B Voodoo and F - 106 Delta Dart were first received by ADC during the first half of 1959 . By 1960 , the ADC interceptor force was composed of the F - 101 , F - 104 , F - 106 , and the F - 102 . The North American F - 108 Rapier was the first proposed successor to the F - 106 . It was to be capable of Mach 3 performance and was intended to serve as a long - range interceptor that could destroy attacking Soviet bombers over the poles before they could get near US territory . It was also to serve as the escort fighter for the XB - 70 Valkyrie Mach - 3 strategic bomber , also to be built by North American . The Air Force expected that the first F - 108A would be ready for service by early 1963 . An order for no less than 480 F - 108s was anticipated . However , by mid - 1959 , the Air Force was already beginning to experience some doubts about the high cost of the Rapier program . The primary strategic threat from the Soviet Union was now perceived to be its battery of intercontinental ballistic missiles instead of its force of long - range bombers . Against intercontinental ballistic missiles , the F - 108A interceptor would be completely useless . In addition , the Air Force was increasingly of the opinion that unmanned intercontinental ballistic missiles could accomplish the mission of the B - 70 Valkyrie / F - 108 Rapier combination much more effectively and at far lower cost . Consequently , the F - 108A project was cancelled in its entirety on 23 September 1959 , before any prototypes could be built . The work on the F - 108 Rapier did not entirely go to waste . The work that Hughes did on the AN / ASG - 18 radar was later transferred over to the Lockheed YF - 12 A interceptor project , and the GAR - 9 Falcon ( redesignated AIM - 47A in 1962 ) missile originally developed for the F - 108A was used to arm the YF - 12A . The Lockheed F - 12 Mach 3 interceptor of the mid - 1960s was the final interceptor planned by Air Defense Command for purchase and deployment . It had its origin in the top - secret A - 12 reconnaissance aircraft which had been designed by Lockheed at Central Intelligence Agency request as a successor to the U - 2 . Three prototype YF - 12As served initially with the 4786th Test Squadron at Edwards AFB . The USAF was sufficiently impressed with the performance of the YF - 12A that on 14 May 1965 they ordered a total of 93 definitive F - 12B aircraft into production and Congress voted $ 90 million toward the project . However , Secretary of Defense Robert McNamara saw no need for the F - 12B due to the development of ICBMs and the diminishing threat of Soviet bombers attacking United States cities . Another reason given by McMamara for cancelling the F - 12 was that the expanding war in Southeast Asia was consuming all available funds in the USAF budget . This was , of course , before the Soviets developed the Tupolev Tu - 22M and Tupolev Tu - 160 supersonic strategic bombers which were at least an even match to the fastest ADC F - 106 Delta Dart . The YF - 12As served primarily in various and sundry operational evaluation projects throughout the remainder of the 1960s . In February 1963 , Lockheed undertook redesign of the basic A - 12 with additional fuel tankage , broader forward nose chines , and the provision for inflight refueling and a seat for a second crewman . This eventually emerged as the SR - 71 Blackbird . In 1968 , ADCOM began the phaseout of the F - 101 and F - 102 interceptors from active duty units . George W . Bush , later President of the United States , flew the F - 102 as part of his Air National Guard service in the late 1960s and early 1970s . The F - 106 Delta Dart remained , as it was considered by many as being the finest all - weather interceptor ever built . It was the primary air defense interceptor aircraft for the US Air Force during the 1970s through the early 1980s . It was also was the last dedicated interceptor in U . S . Air Force service to date . It was gradually retired during the 1980s , though the QF - 106 drone conversions of the aircraft were used until 1998 as aerial targets under the FSAT program . Interceptor gunnery training . B - 57E Canberra dedicated Air Defense Command target towing aircraft were used for training of F - 86D Sabre , F - 94C Starfire , and F - 89D Scorpion interceptors firing 2 . 75 - inch Mk 4 / Mk 40 Folding - Fin Aerial Rocket s . Due to the nature of air - to - air weapon training requiring a large amount of air space , only a few locations were available for practice ranges . ADC assigned these aircraft to bases close to these large , restricted areas , and fighter - interceptor squadrons deployed to these bases for this type of " hot fire " training which took place in these ranges . The gunnery schools were located at Yuma AFB , Arizona ( 17th TTS ) , and later moved to MacDill AFB , Florida where the training continued over the Gulf of Mexico . With the move to Florida , the 3d TTS was formed at George AFB , California which performed training over the Mojave Desert in Southern California . Additional units were located at Biggs AFB , near El Paso , Texas ( 1st TTS ) and the 4756th TTS was located at Tyndall AFB , Florida to support the Fighter Weapons Center located there . ADC also supported overseas training at Johnson AB , Japan ( 6th TTS ) . From Johnson AB , B - 57Es deployed to Clark AB , Philippines ; Andersen AFB , Guam , Naha AB , Okinawa and Itazuke AB , Misawa AB and Yokota AB , all in Japan for training of the interceptor squadrons assigned to those bases . The 6th TTS was inactivated by late 1957 and the Canberra trainers were designated a flight of the 8th Bombardment Squadron at Johnson AB . In Europe , USAFE supported a squadron of B - 57E gunnery trainers at Wheelus AB , Libya where European - based interceptors deployed for " live firing " over the vast desert range there . To provide challenges for interceptors , The B - 57Es towed styroforam , bomb - shaped radar reflectant targets . These could be towed at higher altitudes than the high - drag 45 ' banners but hits could still be scored on them . By 1960 , the rocket firing interceptors were giving way to F - 102 Delta Dagger interceptors firing heat - seeking AIM - 4 Falcon air - to - air missiles . This made the target towing mission of the B - 57E obsolete , and the B - 57Es were adapted to electronic countermeasures and faker target aircraft ( EB - 57E ) ( see below ) . In order to cover combat losses in the Vietnam War caused by two major ground explosions , twelve B - 57Es were reconfigured as combat - capable B - 57Bs at the Martin factory in late 1965 and were deployed to Southeast Asia for combat bombardment operations . Six other B - 57Es were converted to RB - 57E " Patricia Lynn " tactical reconnaissance aircraft in 1966 during the Vietnam War , operating from Tan Son Nhut Air Base until 1971 . Weapons Systems Integration . The development of effective Ground Intercept Radar stations , and the deployment of interceptor squadrons was soon augmented by more - effective systems whose inputs would be fed to one of the bigger gambles of the period — the Semi Automatic Ground Environment ( SAGE ) system , designed to control fighters and fight the air defense battle . As the performance of radars and weapons improved , the reflexes of the men who operated them proved much too slow , By 1953 , steps had been taken develop an electronic command and control network . SAGE had begun as a concept in the Air Defense Systems Engineering Committee , headed by eminent Massachusetts Institute of Technology scientist George E . Valley . Valley foresaw that computers would develop to the point that they could be used to control an air defense system . He was right , and he was backed by ADC commanders throughout the years . SAGE was the nerve center of continental air defense until replaced in the early 1980s . It was an automated control system linking Air Force ( and later FAA ) General Surveillance Radar stations into a centralized center for Air Defense , intended to provide early warning and response for a Soviet nuclear attack . This automated control system was used by NORAD for tracking and intercepting enemy bomber aircraft . In later versions , the system could automatically direct aircraft to an interception by sending commands directly to the aircraft ' s autopilot . SAGE was tremendously important . It led to huge advances in online systems and interactive computing , real - time computing , and data communications using modems . It is generally considered to be one of the most advanced and successful large computer systems ever developed . The first SAGE Direction Center opened at McGuire AFB , New Jersey on 1 July 1958 , and was rapidly joined by others in the eastern and northern United States during 1959 and 1960 . By the end of the decade the blockhouses of the SAGE System could be seen across the nation . By the time it was fully operational the Soviet bomber threat had been replaced by the Soviet missile threat , for which SAGE was entirely inadequate . However , as long as the Soviet Union maintained an active intercontinental bomber force , the system was active , and ready to respond to any incursion of North American airspace . SAGE was inactivated and replaced in 1983 by the Joint Surveillance System ( JSS ) . Anti - Aircraft Missiles . Alongside the manned interceptors was the CIM - 10 Bomarc supersonic surface - to - air missile which - first entered the ADC inventory in September 1959 . The BOMARC was a joint United States of America - Canada effort between 1957 and 1971 to protect against the USSR bomber threat . It involved the deployment of tactical stations armed with Bomarc missiles along the east and west coasts of North America and the central areas of the continent . The supersonic Bomarc missiles were the first long - range anti - aircraft missiles in the world . They were capable of carrying conventional or nuclear warheads . Their intended role in defence was in an intrusion prevention perimeter . Bomarcs aligned on the eastern and western coasts of North America would theoretically launch and destroy enemy bombers before the bombers could drop their payloads on industrial regions . The BOMARC interceptor missile was deployed to a number of sites along the eastern seaboard and northern border . When the BOMARC missile was phased out in the late 1960s , the SAGE guidance system ( TDDL , Time - Division Data Link ) continued to be used for sending commands to Army Nike - Hercules Integrated Fire Control ( IFC ) centers and interceptor autopilots . Defense Systems Evaluation . " Faker " , or simulated target aircraft were flown as simulated target aircraft to exercise GDI stations , interceptor squadrons and SAGE control centers . Initially using modified B - 25 Mitchell and B - 29 Superfortress bombers , the aircraft would fly attack profile missions at unexpected , random times and attempt to evade coverage by flying at low altitudes and randomly flying in different directions to confuse interceptors . The aircraft were modified to carry electronic countermeasures ( ECM ) gear to attempt to confuse radar operators . In 1957 , the propeller - driven aircraft were phased out and replaced by Martin B - 57 medium bombers which were being phased out of Tactical Air Command . Initially RB - 57As from reconnaissance units were modified to have their former camera bays refitted to carry out the latest ECM systems to confuse the defenders . Wing racks , originally designed for bombs , now carried chaff dispensers and the navigator position was replaced with an Electronic Warfare Officer ( EWO ) . The modified B - 57s were designated as EB - 57 ( E for special electronic installation ) . Considerable realism would be generated into these simulated aggressor attack missions being flown by the B - 57 crews . Often several EB - 57s were used to form separate tracks and provide a coordinated jamming attack to complicate the testing . When inside the range of the GCI radar , and in anticipation of interception , chaff was dispensed to confuse the defense force and electronic pulses to jam radar signals were turned on . It was up to the defending interceptors and GCI stations to sort out the correct interception . Units operating these specially equipped aircraft were designated Defense Systems Evaluation Squadrons ( DSES ) . The 4713th Defense Systems Evaluation Squadron was stationed for training in the Northeast . The 4713th also deployed frequently to USAFE in West Germany for training of NATO forces . The other was the 4677th Defense Systems Evaluation Squadron , which concentrated on Fighter Interceptor Squadron training for units in the Western United States . In 1974 , the 4713th DSES was inactivated and its EB - 57s were divided between two Air National Guard units and the 4677th DSES was re - designated as the 17th Defense Systems Evaluation Squadron . This unit was inactivated in July 1979 and was the last to fly B - 57s in the active duty USAF . It shared the Defense Systems Evaluation mission with the Kansas and Vermont Air National Guard . Defense Systems Evaluation operations were also carried out by the 6091st Reconnaissance Squadron , Yokota AB , Japan ; later the 556th Reconnaissance Squadron and moved to Kadena AB , Okinawa . EB - 57s were also deployed to Alaskan Air Command , Elmendorf AFB , Alaska , frequently . The 134th Defense Systems Evaluation Squadron , Vermont Air National Guard , retired its last EB - 57 in 1983 , and the operational use of the B - 57 Canberra ended . NORAD Continental Defense . The Royal Canadian Air Force proved to be a boon partner with the United States , both in the responsibilities it assumed in the construction of the warning systems and in the provision of effective air defense squadrons . In some respects , the air defense mission was to RCAF what the nuclear deterrent mission was to USAF - its No . 1 reason for being In the early 1950s , the two North American air forces launched construction of the Pinetree Line and completed it in June 1954 . Consisting of 33 stations , it extended on both sides of the international border and provided warning and ground - control - intercept activities . The United States paid for 22 of the stations and provided personnel for 18 . Canada then constructed the Mid - Canada Line , building it entirely with its own resources . Built along the 55th parallel , the early warning system was also called the McGill Line , after the scientists at McGill University who planned and designed it . Not so much a radar warning line as an unmanned microwave fence , the line signaled when something - anything - flew over it . The Mid - Canada Line became operational in 1957 and cost approximately $ 220 million . By 1954 it became apparent that the command and control of the massive North American air defense system was a significant challenge . Coordination in the United States was accomplished by a new joint - service agency of Air Force , Army and Navy personnel reporting directly to the Joint Chiefs of Staff and called the Continental Air Defense Command ( CONAD ) . The command and control of the massive North American air defense system was a significant challenge . Discussions and studies of joint systems between the United States and Canada had been ongoing since the early 1950s and culminated on 1 August 1957 , when an agreement was made with Canada to partner in the joint effort to defend the North American continent which resulted in the North American Air Defense Command ( NORAD ) , in which ADC continued to be the major United States component . On 12 September joint operations commenced at Ent AFB , Colorado . A formal NORAD agreement between the two governments was signed on 12 May 1958 . Alaska and above the Arctic Circle . The Alaskan Air Command was established in 1946 with a mission of air defense of Alaska and the Aleutian Islands . With the Soviet Union less than 50 miles to the west across the Bearing Straits , Alaska was the " front line " of North American air defense . A series of Ground Control Intercept and surveillance radar stations and interceptor bases were established there in the 1950s to provide for the defense of northwest North America . Working with Canada , USAF planners began to entertain the prospect of building a warning line in the far north , inside the Arctic Circle . High cost projections disturbed Air Force leaders , who believed the money could be better spent on bomb shelters and base dispersal efforts . However , USAF conducted experiments in conjunction with the Lincoln Laboratory of MIT and became convinced that a Distant Early Warning Line ( DEW Line ) was feasible . Once again working in cooperation with the RCAF , USAF in December 1954 placed a contract for the construction of the DEW Line . The DEW Line , built along an irregular path extending from Cape Lisburne AFS , Alaska , to the west coast of Greenland , with auxiliary stations situated even further east , was a mammoth undertaking . It was the largest construction project ever attempted in the Arctic , and it required the movement of hundreds of shiploads of material and thousands of sorties by American transport airplanes . The workforce toiled day and night , seven days a week , to make the 31 July 1957 , date when responsibility was to be transferred to USAF . Twenty - five lives were lost in the process . The Pinetree , Mid - Canada , and DEW Lines all were integrated into the SAGE system . The " White Alice " communications system was built to link airborne warning and control aircraft with the DEW Line radar . Ultimately , 49 sites were built , extending along the Aleutian archipelago out to Shemya , Alaska . Ballistic Missile Early Warning System . The success of the DEW Line for atmospheric defense of North America from an Arctic attack by Soviet aircraft smoothed the way for the development of an effective defense against the Intercontinental Ballistic Missile ( ICBM ) and Submarine - launched ballistic missile ( SLBMs ) . The Ballistic Missile Early Warning System ( BMEWS ) , which was completed in 1963 after five years of intensive effort provided a capability of detecting missiles in flight , deep in the Soviet Union or in other similarly distant territory . The BMEWS sites included Thule AB in Greenland , Clear AFS in Alaska , and RAF Fylingdales in England . In addition , the number of radar stations had increased dramatically during the decade of the 1950s , with 300 small automatic radar sites adding coverage . Additional radars came into being for the sole purpose of detecting , identifying , tracking , and sending back data on any SLBM . All man - made objects in earth orbit became numbers in the United States Space Surveillance Network ( SPACETRACK ) operated by ADC ' s Fourteenth Aerospace Force . Aerospace Defense Command . As the space mission grew the command changed its name , effective 15 January 1968 , to Aerospace Defense Command , or ADCOM . Under ADCOM , emphasis went to systems for ballistic missile detection and warning and space surveillance , and the atmospheric detection and warning system , which had been in an almost continuous state of expansion and improvement since the 1950s , went into decline . BOMARC , for example , was dropped from the weapons inventory , and the F - 101 and F - 102 passed from the regular Air Force inventory into the National Guard . To save funds and manpower , drastic reductions were made in the number of long range radar stations , the number of interceptor squadrons , and in the organizational structure . By 1968 the DOD was making plans to phase down the current air defense system and transition to a new system which included an Airborne Warning and Control System ( AWACS ) , Over - the - Horizon Backscatter ( OTH - B ) radar , and an improved F - 106 interceptor aircraft . The changing emphasis in the threat away from the manned bomber and to the ballistic missile brought reorganization and reduction in aeropace defense resources and personnel and almost continuous turmoil in the management structure . The headquarters of the Continental Air Defense Command ( CONAD ) and ADC were combined on 1 July 1973 . Six months later in February 1973 , ADC was reduced to 20 fighter squadrons and a complete phaseout of air defense missile batteries . Continental Air Command was disestablished on 1 July 1975 and Aerospace Defense Command became a specified command by direction of the JCS . Reductions and reorganizations continued into the last half of the 1970s , but while some consideration was given to closing down the major command headquarters altogether and redistributing field resources to other commands , such a move lacked support in the Air Staff . Inactivation . In early 1977 strong Congressional pressure to reduce management " overhead " and the personal conviction of the USAF Chief of Staff that substantial savings could be realized without a reduction in operational capability . moved the final " reorganization " of ADCOM to center stage . Two years of planning followed , but by late 1979 the Air Force was ready to carry it through . It was conducted in two phases : ADCOM , as a specified command , continued as the United States component of NORAD , but the major air command was inactivated on 31 March 1980 . The unit designation of the MAJCOM reverted to the control of the Department of the Air Force . . Note : Assigned to Olmsted AFB , Pennsylvania , but never equipped or manned . Not to be confused with Eleventh Air Force , which was assigned to Alaskan Air Command