Warning is an integral part of air defense, but for the purposes of this study it has been separated from its air defense matrix. Our concern with warning in this study of command and control is in terms of its passive detection role. We do not deal with any of the combat aspects of air defense systems.


While the Army Air Forces established the Air Defense Command (ADC) at Mitchell Field, N.Y., on 27 March 1946, the prevailing attitude toward air defense in this early postwar era was one of extreme ambivalence. Air defense was regarded within the air forces as necessary in theory but not in terms of resource allocation. Not surprisingly, therefore, planning for air defense in any practical and coordinated sense got under way late. This resulted also from the unsettled nature of roles and missions before mid-1948, the indeterminate status of Air Force programs and organization, and the cost of attempting to build both air defense and offensive forces.

By the end of 1946 and early 1947, however, world developments had led to some public concern, primarily over the deliberate reliance by the ADC on Air National Guard (ANG) and Reserve personnel to man the few resources it possessed. The first major air defense debate thus began over the issue of whether the United States required an “in-being” air defense system or whether one based on the Air National Guard and Reserve would be adequate.

When the ADC was activated, there was not a single search radar in operation within the United States. General Spaatz, the commanding general, Army Air Forces, revealed before a congressional committee in May 1946 that he had no intention of allocating a substantial proportion of regular AAF strength to air defense, and he declared his intention to rely principally for air defense manning on the ANG and Reserve. He did, however, ask at this time for funds to operate certain radar sites on a 24-hour basis.

The issue that lay behind Spaatz’ attitude was the one that underlay the whole air defense problem and was probably the crucial one in determining the course of events. This was the issue of resource allocation. Most of the AAF/USAF leadership was deeply committed to a concentration of resources on the development and expansion of US strategic striking power. Their view was that this course was dictated not only by the scarcity of funds, but by the absence for some time to come of any real airborne threat from the Soviet Union. Experimenting with air defense seemed a costly and unnecessary enterprise. With the sharply reduced budgets of the late 1940s, the new Air Force would choose to apply its resources to the development of nuclear attack forces, which would be a concrete asset, rather than to the air defense field, which was so dominated by uncertainties.

An issue derivative from the above was whether to postpone the development of an air defense system for several years, both until the threat became more real and by which time newer equipment would be available, or to start now on a system using rapidly obsolescing World War II equipment.

All through 1946 and into 1947, discussion of the real mission of the ADC continued, numerous views being expressed within the Army Air Forces, the other services, and the Congress. One overriding consideration did control the debate. In May 1947, Spaatz directed the ADC not to rock the boat over the matter until the unification of the air forces and budget issues were settled. It must be stressed that, a dominant concern of Army Air Force leaders in 1946-47 was the establishment and organization of an independent US Air Force. The ramifications of this concern were such that, while the issue of resource allocation between strategic offensive forces and air defense continued to be fundamental, in actual fact the United States would have little of either for several years, in good part because of the preoccupation of the Air Force leadership with the creation of the USAF.

Accordingly, steps toward the creation of even a token warning system were halting. In May 1947, operational search radars were set up in Arlington, Wash., and Half Moon Bay, Calif., but they were operated on a part-time basis and were mostly for training purposes. No real action was taken on any of the ADC’s plans until after the establishment of the USAF in July 1947. On 12 November 1947, the Secretary of Defense announced that planning for a nationwide radar early warning system was under way. This was an Air Force plan named SUPREMACY, which was designed to remedy the most fundamental lack in US air defense—an air control and warning (AC&W) system that would cover a very large part of the approaches to the United States. SUPREMACY was to provide a framework for such a system; it called for 223 basic radar stations and 14 control centers within the United States, and 37 basic radars and 4 control centers in Alaska. The plan, however, was too ambitious for the political and budgetary climate and it died when Congress failed to appropriate funds for it.

SUPREMACY did serve the function of raising key issues about air defense and warning. An exchange of memorandums between Secretary Forrestal and the JCS pointed up major issues that ..were to continue for years. The Bureau of the Budget, in May 1948, had sent the Secretary a memorandum that raised questions concerning SUPREMACY. The Bureau wanted to know the relative priority of the program, the extent to which USN picket ships would be used, and how the strength of the -services and the National Guard would be integrated.

A month later Forrestal turned to the JCS for advice. He pointed out the admitted inadequacies of the proposed radar fence against even World War II aircraft and reported that the Research and Development Board thought; that the United States could not expect to obtain more adequate equipment from current development programs for about five years. The Air Force, he said, planned an orderly replacement of older type equipment, at as reasonable a cost as possible, when new types became available. Forrestal continued:

Therefore, a fine question of judgment is involved. On the one hand there are considerations of economy involved in spending a substantial amount of money on radar which is now not completely effective and which will probably be obsolete in a few years, and on the other hand there is the obvious fact that the use of the present types of radar would give us at least some protection against a surprise attack during the years in which superior types are being developed.

The JCS reply came almost four months later, which perhaps indicates something of the priority they placed on air defense. They explained that the Soviets possessed aircraft capable of one-way strikes to any vital target in the United States and that Alaska and the Pacific Northwest were within radius of those aircraft from their present bases. As of September 1948, the Soviets had 210 long-range bombers with this capability, and it was estimated that their force of improved bombers would reach 1,600 by 1952. Furthermore, Soviet development of an aerial-refueling capability was possible. It could be assumed that until 1952 the Soviets would not have the atomic bomb in sufficient quantity to wage atomic war against the United States of such magnitude as to be decisive.

However, by 1953 it was possible that the Soviets might have 20-50 bombs. Until 1953, the JCS felt, the Soviets would have to rely upon-high-explosives, chemical, or bacteriological attacks, which would imply a series of sporadic, harassing attacks.

The JCS pointed out that the present 12 radar control and warning stations had almost negligible value. They recognized that present equipment was only reasonably effective now and would have only limited effectiveness against anticipated Soviet air capabilities in 1953. They therefore recommended the implementation of a modified air defense system that would (a) provide a basic capability; (b) be an operational proving ground for integration and improvement of methods, equipment, and training, both for defensive and offensive purposes; (c) be a deterrent to enemy attack; (d) provide means for the formulation of doctrine and ultimate requirements for joint and civilian participation; and (e) serve as a deterrent to the pressure of public opinion to divert military forces from offensive missions in case of attack. In regard to the Secretary’s query as to priority, the JCS said it was low compared with programs for the offensive, but that the priority would rise progressively with Soviet strategic capabilities.

Nevertheless, the pressures of growing tension in Europe had provoked some action. In March 1958, the Air Force had ordered the Arlington, Wash., radar station on to a 24-hour basis and activated four other radars in the area to cover the Hanford, Wash., nuclear facility. This was probably the initial step in a serious warning system.

A much reduced version of SUPREMACY, called the Interim Plan, was approved by the JCS and the Secretary of Defense in late 1948. This plan was to be completed in 26 months and would include the 5 basic radar stations and 2 control centers currently in operation. With equipment that was in storage or. on order added to the existing facilities, a total of 61 basic radar stations and 10 control centers in the United States and 10 basic radar stations and 1 control center in Alaska would be operational. In addition, 15 more basic radars were scheduled for eventual activation. The Interim Plan system was recognized as being far from ideal, but it did represent what could be accomplished by 1952 with restricted funds. What is significant about it is that by the end of 1948 a token “in-being” air defense system had finally begun to take shape.

The Interim Plan system was approved by Congress in March 1949. However, by this time the need for more immediate protection was recognized, and to fill the gap until the completion of the Interim Plan system, the ADC was directed to establish a temporary AC&W system, to be named LASHUP. This system would consist of 44 stations using World War II radars. Work got under way in late 1948. By the spring of 1949, 18 radars had been deployed to the northeast United States, but LASHUP was not completed until mid-1950.

Although the first plan (SUPREMACY) was submitted to it in late 1947, Congress did not act on a permanent radar system until the fall of 1949, after the first Soviet atomic explosion. During the first half of 1950, however, the Air Force continued to stress the construction of the Interim Plan system, and it was hoped by summer that the system, originally scheduled for completion in 1952, might be operational by mid-1951. By this time the Interim Plan system had merged into the so-called permanent system, so future reference shall be made the later term.


The outbreak of the Korean war, coupled with the Soviet nuclear explosion, provided tremendous stimulus to the development of a comprehensive warning system. The issuance .of NSC 68 added further impetus. Appearing in early 1950, NSC 68 had concluded that by 1954 the Soviets would have the capability to launch a devastating attack on the United States. One recommendation of the report was to build an active air defense that would provide warning of an attack and a means of defeating a bomber attack without resorting to nuclear retaliation initially. The suggested system would include a successive line of trans-Canada radar early warning stations, dispersed interceptor groups, deployment of antiaircraft missiles, an airborne-alert portion of the bomber force, and a hardened and sheltered command and control system to ensure communications. While no immediate action followed, the points made were all prophetic of future developments.

After June 1950, money ceased to be a problem, at least temporarily. The problems now lay not in budgetary constraints but in the slowness of project completion. Deadlines began slipping steadily. Completion date for the permanent system slipped from a firm November 1951 to May 1952.

There was also an increasing realization in the Air Force in 1951 that, despite the sense of accomplishment in that both the administration and the Congress had accepted the requirement of an in-being air defense system and were pouring massive funding into it, the system under development was based upon obsolescent World War II equipment and techniques. In order for the system to be effective for a respectable lifespan, considerable improvement would be needed.

There was also some concern that the public had been oversold or had oversold itself on the capabilities of the air defense of the near future. Official DoD views had been cautious. The Secretary of the Air Force, in his January-June 1950 report, had stated:

Completion of this aircraft early warning system will be an important step forward in the air defense of the US. However, it is only a start and will fall far short of the ultimate goal of a complete radar coverage. Additional stations must be built both in the US and in the North and great technical developments must be made in our scientific centers and labs in perfecting equipment and methods used for detection of aircraft.

These cautions were “too often forgotten. Estimates by authorities in early 1951 that the permanent system would stop only 5-10 percent of an attacking force led DoD to request the Massachusetts Institute of Technology to undertake Project Charles.

The Project Charles report on 1 August 1951 offered no unusual solutions to the dilemmas of air defense. It strongly recommended that the current system be updated by increasing the extent of the radar coverage and also by increasing the speed by which data acquired by radar could be analyzed and acted upon. The report further recommended use of picket ships and airborne radar to provide a measure of offshore coverage. The Ground Observer Corps (see below) could be used to cover low altitudes.

The report said that no new spectacular improvements in radar could be expected, but that great possibilities existed in the use of data automation to improve air defense systems. The scientific personnel who authored the report were convinced that automation was the only means by which speed in radar-data handling could be measurably increased. They called for new computers specially designed for an air defense function. (At this time, automation was just beginning to come into use in industry and its potential was not well understood.)

The Air Force accepted the recommendations in September 1951 and established the Lincoln Laboratory at MIT to continue research in the field.


A civilian support force for warning made its first appearance in September 1949, when personnel from the Office of Civil Defense were used in air defense tests. By December of that year, the USAF was considering a permanent Ground Observer Corps (GOC). Progress in developing a GOC was slow, however, through 1951, and the system itself proved faulty. The reporting and analyzing of data were generally too slow for the sightings. A much more rapid system, along the line of the Project Charles recommendation, was clearly needed. Yet, until a low-altitude radar could be developed, the GOC was the only capability for low-altitude coverage.

Another weakness of the GOC lay in its volunteer nature, which meant that it was not immediately available . It would require three hours’ notice before it was ready to begin to function. An effort in 1951 to get a 24-hour manning for the northeast portion of the United States during the summer months (estimated by Intelligence to be the period of greatest danger) failed. The GOC was finally placed on a 24-hour operational basis in 27 states in July 1952. This was achieved, it should be added, only after a shaky, politics-riven start as a result of the clashing of state and local jurisdictions with the DoD. The system was now given the code name of Operation Skywatch.


Despite progress, there was a certain confusion and lack of decision apparent in warning and air defense planning by 1952 over the issues of the scope and nature of a proper air defense of the United States. It will be apparent that the issues were the same ones that had appeared in 1946-47—how much should be devoted to air defense and what should be expected from it. A 75-station permanent radar system and new radar and aircraft were being produced to replace the older equipment. All had been authorized in 1951, or earlier. The question that came to the fore in 1952 was whether the basic air defense system under construction should be further expanded and improved—at very considerable cost. Discussion was brought into focus by the Lincoln Laboratory Summer Study Group, which recommended construction of a distant early warning (DEW) line across Canada and integrated and fully automated communications for control of the air defense systems, all this at a cost of several billions of dollars.

The DEW line had early antecedents. In 1946, a similar scheme had been proposed by AAF planners but died for economy reasons. In 1947-48, when the USAF was proposing SUPREMACY, the ADC had objected that the plan omitted a line of land-based radars along the farthest reaches of North America, a system the ADC called essential since the Soviets were then capable of a B-29-type aircraft assault across the North Pole. A distant early warning line could provide three-six hours of extra warning. The ADC’s efforts in 1948-49 failed, because no real threat was yet perceived in view of the US nuclear monopoly.

Some intermediate efforts were made to piece together AC&W programs in Canada and Alaska. One control center and 10 radar stations were planned for completion in 1952, but these ultimately became operational under the Alaskan Air Command only in early 1954. While US-Canada discussions dated to 1940, serious joint consideration of air defense did not begin until April 1949. A US-Canada agreement was signed in 1951, under which a total of 33 AC&W stations would be built in Canada, 22 by the United States and 11 by Canada. Eighteen would be manned by USAF personnel and 15 by Canadians. Of the US sites, 8 were assigned to the ADC and were operational by mld-1954. The other 10 US sites, deployed along northwest Canada from Baffin Island across Labrador to Newfoundland, were assigned to the Northeast Air Command. In addition, 10 permanent radars were to be erected in Greenland and Iceland to extend coverage eastward.

By the end of 1951, however, only five air defense radar stations were operational in Canada with Canadian manning. The Canadians were using World War II equipment and operating only eight hours a day; the Canadians said they could not begin full-time manning until sometime in 1952.

The patched-together system thus created provided some measure of protection against B-29-type bombers, but it-was obviously going to be inadequate against the threat expected in the 1956-60 period. Production of Soviet Jet aircraft similar to the B-47 was predicted for the late 1950s, with even faster models to come. The increased speed of Soviet aircraft dictated the need to push a detection .line farther out in order to make up for the increment of lost time. Consequently, a joint US-Canadian military study in 1953 agreed to a 1950 Canadian plan to set a line of radars across Canada at 54° or 55° N, to be called the Mid-Canada Line, with an operational date of 1957.

A very distant early warning line concept had been resurrected by Project Charles in August 1951, which concluded that a few hours extra warning would be invaluable. The Lincoln Laboratory Summer Study Group in August 1952 had suggested a line of radars along 70° N, connecting Alaskan radars with those of the Northeast Air Command. Locked onto the ends of this line would be a series of over-water stations flown by AEW&C patrols. Neither DoD nor the Air Force was enthusiastic and the report was not immediately approved. Both were concerned primarily over costs. The USAF opposed the Summer Study Group recommendation, essentially on the basis that the strategy of deterrence did not require such an enormous allocation of resources to air defense systems. The Air Force argued that available equipment did not possess the very high standards of technological excellence that were demanded by such a harsh environment as in the Far North. Furthermore, a DEW line concept was disparaged as potentially creating a Maginot Line mentality that could create a false sense of security. With these views, the Secretary of Defense tended to agree.

Opposition to the distant early warning line came from varied sources. The Commander of the ADC, General Chidlaw, favored, prophetically, concentration of resources on a ballistic missile defense system. A RAND study of the DEW Line concept in November 1952 also opposed it. Such a huge undertaking would necessarily be contingent upon a great increase in air defense funds sufficient to activate other air defense steps-first, such as development of a low-altitude radar screen for the United States, establishment of AEW&C and picket-ship coverage off either coast, and major improvement in the permanent warning system. Also, a very crucial point was that no such great commitment of resources to the Arctic should be made until communications between the United States and the Arctic could be thoroughly tested and proved. The Air Force declined to recommend the Summer Study report to the National Security Council, but in September 1952 the chairman of the National Security Resources Board took it to the NSC. The Air Force concern was the old one, that NSC consideration could end by compelling the Air Force to spend heavily on defense systems at the expense of the deterrent forces.

The NSC took no concrete action, except to request further study of the report. However, the findings of the Summer Study Group were leaked to the press and became the subject of a public debate in which advocates of concentration of resources on the deterrent forces were depicted as being too cavalier with the safety of the United States. This was an unfortunate interpretation of the issue, which was really one of competition for funds and a matter of proper timing for such major undertakings.

Late in 1952, the President decided to issue a policy statement on a warning system. The services and the JCS unanimously opposed what was first expected to be a public statement. The flurry that was created led to some very specific statements of the fundamental inhibition felt by most Defense official’s, military and civilian, over air defense programs. The Secretary of the Air Force, for example, cautioned the Secretary of Defense that “we must give full weight to the deterrent as well as to the air defense function in any considerations. There must be no withdrawal from or diminution of established national policy which holds that a strong offensive capability is the greatest single deterrent to war.”

The Secretary of the Air Force also suggested that a presidential statement on warning might result in accentuating early warning to the detriment of other known defense measures, as well as offensive striking power. If so, the buildup of “known quantities would be impaired in favor of what thus far is still a pig in a poke.” He also cautioned about announcing completion dates or estimates of cost. He stated that “we must have as effective an early warning system as American ingenuity can provide, but, in the national interests, this project must be viewed in proper perspective.”

The President and NSC took account of the solid front against any public statement and revised the policy statement accordingly. It appeared as NSC 139 on 31 December 1952, a top secret document. It stated that the estimated time scale on which the Soviet Union would possess sufficient atomic weapons to deliver a heavy attack on the United States indicated that the United States should plan to have an effective system of air, sea, and land measures ready no later than 31 December 1955 – An early warning system that would provide three-six hours warning was desired, and as much of the system as possible should be completed by 31 December 1954 and the full system completed by 31 December 1955.

The episode illustrated well the perpetual issue that overhung all warning and air defense developments, that of offense versus defense. Up until this point, the proponents of heavy emphasis on offensive measures and capabilities had been dominant.

In the meantime, despite the lack of any decision on an improved air defense and warning system in 1952, the existing permanent system was extended. Forty-four mobile radar stations were approved and in July the ADC requested 35 more. At the end of the year, the ADC was operating 81 radar stations within the United States. Of these, 75 were part of the permanent network and 6 were LASHUP radars of the earlier system. Nine stations were operational in Canada, 2 from the approved 33-station Canadian extension of the permanent system, and 7 of the LASHUP type.

Thus a basic “in-being” air defense was operational, although mostly of World War II type. The radar stations of the permanent system and the GOC in 27 states were sending data to 11 control centers. Thirty-nine Interceptor squadrons backed up the system. One-third of these were early model all-weather jets (F-89B/C and F-9WB), while 15 squadrons had fighters capable of daylight operations only (F-80, F-84, and F-86). Eleven squadrons still had World War II piston-engine fighters (F-47 and F-51).

The DEW Line controversy carried over into the new Eisenhower administration. The hearings on the last Truman budget began in early March 1953 and immediately bogged down over the air defense issue. General Vandenberg, the Chief of Staff of the Air Force, stressed that the goal suggested by the Summer Study Group of a 25 percent attrition of an attacking force was gilding the lily and did not represent a reasonable objective. The issue posed a dilemma for the new Eisenhower administration, which had been elected on an economy-in-government campaign and now faced major outlays for air defense, outlays over which there was no general agreement. The administration and the NSC tended to divide over the issue.

The Kelly Committee, appointed in late 1952 to examine overall US defenses, reported in May 1953 that, while the principal element of American defense was the strategic striking force, a better air defense system, especially an early warning system, was needed. The report could thus be used by both opponents and proponents of the Summer Study Group recommendations. However, the Committee did play down the need for haste in continental defense and rejected the idea of a rush program.

With the administration still undecided, Secretary of Defense Wilson appointed another committee, under Maj. General Bull’s chairmanship, to study the air defense issue. Bull’s group reported to the NSC in July 1953 that existing air defense plans were entirely inadequate and estimated that needed improvements might cost $18-$25 billion. The report was not acted on by the NSC.

The JCS position on expenditures of this magnitude reflected the position of those who stressed offensive deterrent power. In a memorandum to the Secretary of Defense on the matter of continental defense, the JCS summed up their philosophy. Decrying the “inadequacy of intelligence” and calling for better intelligence on Soviet capabilities as a basis for threat projections, the JCS stated:

In weighing the effectiveness of defensive measures against the costs involved, the JCS feel that substantial improvement is possible at a modest cost. Yet there comes a point where a comparatively small increase in effectiveness becomes increasingly expensive until it reaches a point where even great expenditures fail to raise significantly the effectiveness of defenses. An aggressor nation will be far more deterred by evidence that we have the offensive potential and the mobility capable of dealing it decisive blows than by the excellence of our defenses.

The Summer Study Group, however, seemed vindicated in its criticism of the inadequacy of the warning and air defense system by Exercise TAILWIND in July 1953. The Strategic Air Command sent 94 bombers against the air defense system, employing all the techniques available to it—night attack, surprise; diversionary attacks, electronic countermeasures, saturation attack, and so on. Only 7 attackers were successfully intercepted. The following day, against daylight attacks, the air defense intercepted 29 out of 38 SAC task forces. Yet obviously, a real attack would come by night. The exercise pointed up the need for better early warning, solid radar coverage from 0 to 50,000 feet, and some automatic means of tying together data and displaying them to the battle commanders.

What finally broke the back of opposition to a DEW Line was the first Soviet thermonuclear explosion in August 1953. The JCS soon after identified continental air defense and massive retaliation as the two principal military problems facing the country, while on 26 August, Admiral Radford, the new Chairman of the JCS, in his first press conference declared that the Soviet thermonuclear development would compel the United States to review and to strengthen its air defenses. The questions of US thermonuclear development had been debuted earlier in the year, with leading members of the scientific community linking their opposition to development with the air defense issue. Their position was that with a sufficiently tight air defense there would be no need for massive offensive operations that would require thermonuclear weapons. In the debate, supporters of thermonuclear weapon development and of the primacy of the deterrent mission were again portrayed as the villains.

On 6 October 1953, the NSC approved NSC Paper 162, which included most of the Summer Study Group’s findings, of which a DEW Line and automation were the most significant. The NSC was apparently convinced that the large expenditures necessary to make automation in air defense a reality should be spent, notwithstanding the fact that automation was a new thing and nobody was certain what obstacles lay in the way of such large-scale applications of automation.

In late 1953, the Air Force, reflecting the NSC action, approved FY55 funding for 29 more mobile radars (Phase III of the Mobile Radar Program), 5 Texas towers for offshore radars, a Canadian radar line along the 55th parallel, and 323 small gap-filler radars for low-altitude coverage. Inclusion of the 55° line indicated the continued reluctance of the Air Force to build a DEW Line farther north.

The small gap-filler radars were meant to remedy deficiencies in existing radars, and would be unattended stations. Eventually they would replace the GOC, until then the only means of low-level coverage, which was proving to be a weak reed. Only about 11 percent of the personnel the ADC felt were needed were active, public apathy having taken its toll.