Strategic bombers exercised a major influence over the first half of the Cold War, principally because in the 1940s and 1950s they were the only practicable means of delivering the very heavy atomic and hydrogen weapons over intercontinental ranges.* Allied to this, bombers had played a major role in the recently concluded Second World War, with the Allied bombing campaigns against Germany and Japan giving the appearance of a war-winning strategy. Indeed, the war had been brought to a close by the two USAAF (United States Army Air Force) B-29 bombers which dropped atomic bombs on Hiroshima and Nagasaki.
There were also bureaucratic reasons for the fierce advocacy of the bomber, however. The US air force finally became independent of the US army in 1947 and was extremely keen to prove itself to be the war-winning arm in the Cold War. In the UK, which found itself facing the reality that it was now only the second most powerful nation in the West, membership of the exclusive ‘nuclear club’ appeared to be the only way to retain superpower status, and, in the short term, bombers were the only feasible way of achieving that. On the Soviet side, the air force realized that it had never produced a bomber force to match those of the USA and UK, and was desperate to rectify this. Thus, from 1945 into the mid-1960s, the strategic bomber armed with nuclear weapons was the symbol of global power.†
The original atomic bomber – and, after fifty years, still the only aircraft to have dropped atomic bombs operationally – was the piston-engined Boeing B-29 Superfortress, which entered service in 1943 and was the USA’s frontline bomber in the last year of the war against Japan and, with Strategic Air Command (SAC), in the early years of the Cold War. The early atomic bombs were large and very heavy, and the B-29 carried two, but with a range of 5,250 km it could not reach all parts of the USSR from bases in the United States. Thus, in the early Cold War period it was regularly deployed overseas, particularly in the UK, Okinawa and Guam. The B-29 was also provided to the UK air force from 1950 to 1958 (as the Washington B.1), albeit only as a conventional bomber. The B-29 was replaced in US (but not in British) service by an upgraded and more capable version, the B-50.
The Convair B-36 was the largest bomber ever to enter service. Its design had started in 1939–40, when it appeared possible that the UK would be overrun by the Germans and there was a perceived requirement to bomb targets in western Europe from bases in North America. Once it became clear that the UK would survive, however, the B-36 was given a lower priority, and it did not enter service until 1948. It was powered by six piston and four turbojet engines, which gave it the unprecedented unrefuelled range of 13,000 km.
The first major all-jet bomber was the Boeing B-47, which entered service in 1950; by the end of the decade, 1,260 B-47s were in front-line service with twenty-eight SAC bombing wings. At that time the traditional bomber was large, slow, powered by four piston engines, manned by a crew of ten to twelve men, and defended by numerous gun turrets, but the B-47 completely changed all that. It had swept wings and tail, was as fast as contemporary fighters, was powered by six jet engines in neat pods under the wings, carried a crew of three, operated 3,000 m higher than previous types, and was defended only by a single, remotely controlled turret in the tail. The problem was its relatively short range of 5,800 km, which again was partially compensated by forward deployment (e.g. to the UK) and partly by the large-scale introduction of air-to-air refuelling.
The mainstay of SAC’s bomber force for most of the Cold War was the Boeing B-52, which was designed in the late 1940s, entered service in 1955, and was still in front-line service at the end of the Cold War. When it entered service the B-52 set new standards for strategic bombers in almost every respect, including the carriage of eight nuclear bombs or up to 40,000 kg of conventional bombs over ranges of up to 12,900 km. In all, 744 were built, many of which were rebuilt several times to keep the force up to date. Although the B-52 started its career as a nuclear bomber, it changed from a high-level to a low-level role, while from the mid-1980s onwards it became a missile launch platform – a less demanding role and more suited to the venerable age of the airframes.
The most dramatic bomber to serve with SAC was the tailless, delta-winged Convair B-58, with a Mach 2 speed and 8,250 km range. Air-to-air refuelling enabled the B-58 to undertake long flights (e.g. from Tokyo to London), loudly advertising its wartime capabilities. The aircraft used a unique system in which a large pod under the fuselage housed both the nuclear weapon and the fuel for the outward flight; it was dropped complete, enabling the aircraft to make a very rapid getaway before returning to base on its internal fuel supply. Although generally successful, the B-58 was very expensive to operate, even by US standards, and was retired after just ten years’ service, without replacement.
Every development after the B-52 proved to be controversial, and the FB-111 was no exception. The original concept, known as the Tactical Fighter Experimental (TFX), was for one basic design which would meet the needs of the US air force, navy and Marines, as well as selling widely to US allies. In the end only the US and Australian air forces bought it, although the UK’s nearly did so, after the cancellation of its own strike bomber, the TSR-2. Almost inevitably, the widely disparate requirements could never be satisfied, although a very effective low-level strategic bomber was eventually produced, with 437 of various marks entering service. FB-111s could carry a maximum of six Short-Range Attack Missiles, each with a 200 kT nuclear warhead, or six gravity nuclear bombs. The greatest significance of the FB-111 was its ability to operate at very low levels at high speeds, and aircraft based in the UK were targeted on heavily defended, large area targets in the western USSR.
One of several abortive attempts in the 1960s to produce a new strategic bomber was the XB-70 Valkyrie, a six-engined behemoth and the largest bomber ever built. The B-70 was intended to fly for long periods at Mach 3 at high altitude, but its extraordinary performance was paralleled by its enormous costs, and after a spectacular crash in which one of the two prototypes was destroyed the whole project was cancelled.
The US air force’s final Cold War bomber was the B-1, which had a very protracted gestation, its official designation of AMSA (Advanced Manned Strategic Aircraft) being misinterpreted by cynics as ‘America’s Most Studied Aircraft’. One particularly strong argument in the early 1960s against the project was simply to question the need for a new manned bomber at all, since vast sums were already being spent on ICBMs, on upgrading B-52s for the air force, and on building new SSBNs and SLBMs for the navy. Even those who supported the need for a new bomber could not agree on what sort of aircraft was needed, but in 1971 the air force placed an order for an initial quantity of four B-1As, a four-engined, swing-wing aircraft, capable of Mach 2 at high altitudes. The first prototype flew in 1974, but when the Carter administration assumed power in January 1977 it gave high priority to an antagonistic examination of the project, which led to its cancellation, virtually in its entirety, that June. When the Reagan administration took over in 1981, however, the air force proposed a new version of the aircraft, optimized for low-level, stealthy penetration, which emerged as the B-1B. An order for 100 was placed, and they entered service from 1985 onwards.
In the low-level penetration role the B-1B flew at Mach 0.85 at a height of about 60 m. The B-1B defended itself partly through very sophisticated electronic-warfare equipment, but also through ‘stealth’ design, it being claimed that the B-1A had a radar cross-section (RCS) one-tenth that of a B-52, while the B-1B had an RCS one-tenth that of the B-1A. Payload comprised various combinations of Air-Launched Cruise Missiles, Short-Range Attack Missiles and nuclear gravity bombs.
At the start of the Cold War the Soviet Union saw itself as threatened by the long-range bombers of the USA but without any effective means of retaliation. For some years the Soviet air force depended upon a copy of the B-29, which had been reverse-engineered (i.e. copied) from three USAAF aircraft which had landed and been interned at Soviet airbases during the Second World War. Designated the Tupolev Tu-4 (NATO = ‘Bull’), large numbers served with the Soviet air force and thirteen were passed to the Chinese air force, which also used them for a time as nuclear bombers. The Tupolev bureau designed improved and larger versions of the Tu-4, but the Soviet leadership decided not to develop piston-engined bombers any further and to concentrate on the development of turboprop and turbojet designs.
The first Soviet design to enter service, in 1954, was the Tupolev Tu-16 (NATO = ‘Badger’), which was similar in capability to the US B-47 and the British Valiant (see Chapter 12), but with only two engines. Unlike those American and British designs, however, the Tu-16 remained in service for many years, with over 2,000 being built, of which the majority were still in service at the end of the Cold War. There were numerous versions, but the nuclear version carried two nuclear bombs in an internal bomb bay, and 287 of this strategic-bomber version remained in service as late as 1987. The Tu-16 was capable of carrying its maximum load of two nuclear weapons over a range of some 4,800 km at a speed of 780 km/h, which enabled it to threaten targets in Europe, Alaska and Japan, but not in the continental USA.
As the US progressed to the Convair B-58, so too did the Soviet air force develop supersonic bombers: the Myasishchev M-4 (NATO = ‘Bounder’), which progressed no further than the prototype stage, and the Tupolev Tu-22 (NATO = ‘Blinder’). The Tu-22 was a large and sophisticated aircraft, with highly swept wings and two massive turbojets in the tail, giving it a dash speed of Mach 1.4 at 12,000 m. Payload was either two nuclear gravity bombs carried internally or a ‘Kitchen’ cruise missile. Combat radius at high altitude was 2,250 km, with a 400 km supersonic dash over the target (or less at low level).
The Tupolev design bureau also produced the Tupolev Tu-20 (NATO = ‘Bear’) – a remarkable design, which first flew in 1955 and entered service in 1956. To the astonishment of Western observers, this aircraft combined swept wings with turboprop engines, and, despite its undoubted success, it remains the only aircraft to combine these two features. The Tu-20 had the immense range, without air-to-air refuelling, of 14,800 km with a payload of at least four nuclear bombs. It was regularly underrated by Western observers, especially in the Pentagon, despite regular non-stop flights by both military and civil versions from the USSR to Cuba. A variety of versions were still in wide-scale service at the end of the Cold War.
Strategic versions were the Bear-A bomber, carrying two nuclear gravity bombs, the missile-carrying Tu-95 Bear-B, carrying a huge AS-3 (NATO = ‘Kangaroo’) cruise missile with an 800 kT nuclear warhead and a range of some 680 km, and the Bear-H attack version, which carried four AS-15 ‘Kent’ cruise missiles, with a range of 3,000 km. All types of Bear regularly carried out training missions against NATO countries, approaching to within some 80 km of the US and British coasts. On an operational sortie against the USA, however, it would have had to fly at medium and high altitudes to obtain maximum range, which would have made it vulnerable to US and allied fighters.
Contemporary with the US B-52 was the Myasishchev M-6 (NATO = ‘Bison’), a large swept-wing strategic bomber, powered by four turbojets, rather than the Tu-20’s turboprops. The large number of M-6s dreaded by the West never materialized, as their performance – particularly the range and the size of the bomb bay – never quite met the operational requirement, and the M-6 was then used for reconnaissance and electronic-intelligence tasks; however, it was symptomatic of the atmosphere of the time that its appearance in 1955 caused much excitement in the United States and led to a great increase in the production rate of the B-52. Like the Bear, the M-6 would have had to approach the USA at medium to high altitudes.
In 1969 US satellites began to return photographs of a new Soviet bomber on the apron at the new aircraft factory at Kazan. This turned out to be a swing-wing version of the Tupolev Tu-22, designated Tu-22M (NATO = ‘Backfire’). Subsequently, a virtually new aircraft with some external similarities to the Tu-22M appeared and was put into production as the Tu-26 (NATO = ‘Backfire-B’). (The relationship between the Tu-22M and the Tu-26 was probably similar to that between the American B-1A and B-1B.)
Three versions of the Tu-26 entered service, one of which carried nuclear weapons for use in the land-attack role. There were, however, repeated arguments between the United States and the Soviet Union over the role of this bomber, with the former stating and the latter denying that it was a strategic bomber. This became a major issue in the SALT II negotiations, and President Brezhnev eventually ordered that the aircraft’s flight-refuelling probes be removed to prove that it did not have the ability to reach the USA, although since these could have been replaced in less than thirty minutes this was only a token gesture. The Tu-26 entered service in the mid-1970s and was produced at the rate agreed under SALT II – thirty per year – with service numbers peaking at about 220.
Finally came the Tupolev Tu-160 (NATO = ‘Blackjack’), which flew for the first time in 1981 and just eighteen entered service from 1987 onwards. With a maximum take-off weight of 275,000 kg this was the heaviest combat aircraft ever built, and it carried a payload of 16,330 kg. The Tu-160 was fitted with swing wings and powered by four very powerful turbojets, giving it a range of 14,000 km at a height of 18,300 m, with a cruising speed of 850 km/h and a dash speed of Mach 1.9. The Tu-160 was also capable of low-level attack. Two large bomb bays could house nuclear gravity bombs, short-range missiles, or air-launched cruise missiles. Ironically, this remarkable aircraft – one of the finest bombers ever built, which at long last gave the Soviet Union the strategic bombing capability it had always sought – appeared just as the Cold War came to an end.
Bomber designers and the tacticians fought an unending war against the potential defenders in an effort to ensure that the bomber would get through to its targets. In the late 1940s the major threat came from radar-directed anti-aircraft guns, which had reached a considerable degree of sophistication, and the bombers’ first response was simply to fly higher than the effective ceiling of the guns. The next threat was air-defence fighters, and here again the bombers responded by flying higher and faster – there were numerous reports of British and US reconnaissance flights over the USSR in the early 1950s in which the Soviet fighters simply could not reach the same altitude as the intruder.
Second World War bombers were fitted with machine-guns in a variety of positions – including the nose, the waist, above and below the fuselage, and the tail – but these were rapidly reduced to just the tail, the elimination of the others saving considerable weight and enabling the aircraft to fly higher and faster. Also in the Second World War, bombers had been escorted by fighters, particularly on the USAAF’s daylight raids; but the strategic ranges now being flown were far in excess of anything a fighter could undertake. So in the 1950s the US air force trialled the idea of the B-36 bomber taking a fighter with it, with the latter being carried on a retractable cradle from which it could be launched in mid-air to deal with enemy fighters, then being recovered for the return to base. A special miniature fighter, the McDonnell XF-85 Goblin, was tested, as was the RF-84K, a modified version of the full-size F-84 Thunderjet fighter, but, although launching proved feasible, recovery did not, and the idea was not pursued.
Electronic countermeasures (ECM) were always used, becoming increasingly sophisticated as time passed. Thus electronic jamming was used to confuse enemy radars, as was ‘chaff’ (strips of metal foil cut to the wavelength of the radar), which was dropped in large quantities, either by the bomber or by specialized escorting aircraft.
One of the earliest devices to help the bomber get through was the US air force’s ADM-20 Quail, which resembled a miniature unmanned aircraft and was dropped over enemy territory, where it flew for some 400 km, using its on-board ECM devices to confuse the enemy as to the strength, direction and probable targets of the incoming bomber force. A maximum of three Quails could be carried by a B-52, and the device was in service from 1962 to 1979.
The main emphasis then turned to stand-off missiles – a concept which, like so many others, had its genesis in Germany, where V-1 missiles had been launched from Heinkel He-111 bombers in 1944–5. The Cold War missiles carried a nuclear warhead and were designed to be launched from the bomber while still outside the range of the enemy air defences. One of the first was the US Hound Dog – a slim missile with small delta wings, and powered by a turbojet – which entered service in 1961. Two Hound Dogs, each with a 1 MT nuclear warhead, were carried beneath the wings of a B-52. The missile could be set to fly at any height between about 50 m and 16,000 m, and had a range at high level of 1,140 km, less at low level. The guidance system was capable of high- or low-level approach, with dog-legs and jinxes to confuse the defence.
Next came the unhappy saga of Skybolt, which was an attempt to use a bomber to launch a ballistic missile, which would have given longer range and, of greater importance, a much shorter flight time. The UK air force joined the project, but the incoming Kennedy administration unilaterally cancelled it in December 1961 – greatly to the indignation of the British, who used the issue as a lever to obtain Polaris missiles and SSBN technology to replace its V-force bombers (see Chapter 12).
The Short-Range Attack Missile (SRAM), which entered service in 1972, was a rocket-propelled missile with a 170 kT nuclear warhead and a speed of Mach 3. SRAMs could fly either a semi-ballistic, a terrain-following or an ‘under-the-radar’ flight profile, the latter terminating in a pull-up and high-angle dive on to the target. The range depended on the height, and was from 56 km at low level to 170 km at high level. B-52s normally carried twenty SRAMs, while the FB-111A carried six and the B-1B twenty-four.
The Air-Launched Cruise Missile (ALCM) entered service with the US air force in 1982. This weapon had folding wings which extended when it was dropped from the carrier aircraft, and was powered by a small turbojet engine. Designed exclusively for low-level flight, the ALCM used a radar altimeter to maintain height and a map-matching process known as terrain comparison (TerCom) to give very precise navigation. The nuclear-armed version (AGM-96B) had a 200 kT warhead, a CEP of 30 m and a range of some 2,500 km. The AGM-96C was conventionally armed, with a high-explosive warhead, and this version demonstrated its effectiveness and accuracy when thirty-five were launched by B-52s during the Gulf War. B-52s could carry up to twelve and B-1Bs twenty-four.
Soviet stand-off missile development followed a similar pattern and time-scale, although in the early stages of the Cold War the missiles tended to be much larger and less effective than their US counterparts. Indeed, the first missile designed for use by strategic bombers, the AS-3 (NATO = ‘Kangaroo’) remains the largest air-launched missile to go into service, with a length of some 15 m, a wingspan of 9 m and a weight of 11,000 kg; only one could be carried by a Tu-95 (Bear-B). It did, however, have a useful range (650 km) and a high speed (Mach 2), and with an 800 kT warhead it was targeted against large area targets such as cities and ports.
The AS-15 (NATO = ‘Kent’) was much smaller and generally similar in size, performance and role to the US Tomahawk; sixteen could be carried by the Tu-95 Bear-B and twelve by the Tu-160 Blackjack. It carried a 200 kT nuclear warhead and flew at high subsonic speeds over a range of some 3,000 km at a height of 200 m, with an accuracy (CEP) of 150 m.
Manned aircraft offered certain unique advantages. First, they possessed inherent flexibility, in that they could be launched on receipt of strategic warning and then be held in the air, diverted to airfields outside the threatened area, or recalled to base. The fact that men were aboard and in control meant that targets could be changed during flight, that moving targets or even targets of opportunity could be engaged, and that orders could be altered or countermanded. Also, unlike with SSBNs, there were excellent communications between the command centres and the airfields, and between the ground and the aircraft. Finally, the bomber-delivered gravity bomb was the most accurate of any nuclear delivery system.
Among their disadvantages, however, was the bombers’ vulnerability to air defences and their absolute dependence on airfields with large runways and extensive maintenance facilities. Every airfield capable of taking strategic aircraft was known to both sides throughout the Cold War, and there can be no doubt that they were primary targets for both conventional and nuclear strikes.
At the start of the Cold War all that the strategic bomber had to do was to fly high and reasonably fast to reach its target, and even if it was picked up by enemy radar there was little that the enemy could do about it. Thus, throughout the late 1940s and most of the 1950s, bombers of Strategic Air Command could quite safely overfly almost anywhere on earth, since anti-aircraft guns could not fire high enough and contemporary fighters’ ceilings were too low to threaten them. That changed, however, in the mid/late 1950s as the performance of Soviet fighters improved, and in particular when they were fitted with airborne radar, enabling them to find and track targets in the dark and in bad weather. At first, bombers sought to counter this by flying even higher and faster, but then yet better fighters and in particular the fielding of air-defence missile systems caused different solutions to be sought.
The advantages offered by bombers over missiles depended upon the aircraft getting airborne in the first place, and in the worst-case situation of an ‘out-of-the-blue’ missile attack the bombers might only receive some seventeen minutes’ warning in the USA (less if the missiles were launched from Yankee-class SSBNs off the US coast) and four minutes in western Europe. Western bombers were therefore placed on a high-readiness status, known as Quick Reaction Alert (QRA). In the UK’s V-force, for example, this was introduced in early 1962 and involved one aircraft in each squadron being at fifteen minutes’ notice twenty-four hours per day, 365 days per year. Bomber Command stipulated that, apart from the aircraft on QRA, 30 per cent of the available aircraft (i.e. those not on major servicing or overseas) should be ready to deploy after four hours, rising to 100 per cent after twenty hours.1
Bomber fleets are almost always listed by total numbers, but this is misleading and nothing like that number would have reached the target in an unexpected crisis. A proportion would always have been in deep maintenance or rebuild, while others would have been simply unserviceable at the time they were required. In addition, it was not unknown for major problems to be discovered en route to the holding position which would prevent the aircraft proceeding to its target. Finally, at least some would have been either shot down or damaged by air-defence missiles, fighters and, on low-level missions, anti-aircraft artillery.
SAC’s bomber force was for a long period the most powerful single strategic military force in the world, with vast numbers of the most modern bombers deployed at bases across the continental United States. The first overseas protracted deployment was to the UK in July 1948, in response to the Berlin crisis (see Chapter 32), when three British airfields were made available to six squadrons of SAC’s B-29s, although these were not, as was reported at the time, atomic bomb carriers (which were known as ‘Silver Plate’). What was originally described as a temporary deployment rapidly became permanent, and, when the NATO Treaty was signed, the number of SAC bases in the UK increased from three to seven, then to eight, and Silver Plate B-29s arrived for the first time. Their targets at that time were in the southern USSR, their routing being over France and then along the northern Mediterranean and across the Black Sea and into the Ukraine and southern Russia. Other SAC bases were in Alaska, the Azores, Guam, Libya, Morocco, Okinawa and the Philippines, although SAC aircraft also made temporary deployments to many other friendly countries.
For all their advantages, strategic bombers inevitably took many hours to reach their targets. This was not a serious drawback when they were the only means of attacking the enemy, but when ICBMs and SLBMs entered the nuclear plan, with their flight times of approximately thirty minutes, bombers were perforce relegated to the second wave. Their missions could include non-time-urgent targets or simply ‘filling in the gaps’ which malfunctioning missiles or warheads left in the missile targeting plan.
A map of planned US strategic attacks on the Soviet Union which was prepared in the early 1950s as part of Operation Dropshot shows SAC bombers attacking from bases in the continental USA, Alaska, Okinawa, Guam, Egypt, Aden and the UK. The mission was to:
initiate, as soon as possible after D-day, strategic air attacks with atomic and conventional bombs: against Soviet facilities for the assembly and delivery of weapons of mass destruction; against LOCs [lines of communication], supply bases and troop concentrations in the USSR, in satellite countries and in overrun areas, which would blunt Soviet offensives; and against petroleum, electric power and steel target systems in the USSR.2
One of the most significant developments was the introduction of air-to-air refuelling, which extended the bombers’ range very considerably. The Boeing KC-97E tanker entered service in the early 1950s, and the Soviets, British and French all subsequently introduced similar systems.* The US and French air forces used a ‘flying-boom’ system, in which an operator in the tanker steered a boom into a receptacle on the upper surface of the receiving aircraft. The British, however, used a ‘probe-and-drogue’ system, in which the tanker streamed a rubber hose from a drum and the pilot of the receiving aircraft manoeuvred until the probe on his aircraft engaged in the drogue at the end of the hose. The Soviets initially used a third method on their Tu-16 Badgers, which involved connecting a hose between the wing-tips of the two aircraft, but this was later replaced by the ‘probe-and-drogue’ method.
Various aircraft were pressed into use as tankers. The US air force policy was to manufacture tanker versions of civil airliners, with the KC-97 Stratotanker being based on the Boeing Stratocruiser, the KC-135 on the Boeing 707, and the KC-10 Extender on the Douglas DC-10. The British, who came to the tanker scene a little later than the Americans, tended to convert service or civil aircraft which had been made redundant from their existing tasks. The first two (Valiant and Victor) were converted from bombers, while the latter two (VC-10 and Tristar) were converted from airliners.
Strategic bombers did not necessarily have to return to the bases from which they had been launched, and, in order to obtain the maximum range, many nuclear missions were planned in which the aircraft would have recovered to a distant base. Thus, for example, a bomber which took off from the continental United States might have flown over the Arctic, launched its missiles or dropped its bombs on targets in the USSR, and then carried on to land in Turkey or Pakistan.
There were, however, frequent (but never confirmed) reports that at least some missions were planned as ‘one-way’, with the best that the crew could hope for being a parachute drop into enemy territory. The respected aviation author Bill Gunston, writing about French Mirage IV bomber, states that: ‘Even with tanker support, many missions have been planned on a no-return basis …’3 There were similar reports about RAF Canberra bombers based in Germany.
Although perhaps not typical of a nuclear attack, the bomber raids carried out by US forces on North Vietnam during Operation Linebacker II give an illustration of the ‘state of the art’ in the early 1970s. The USA made great use of air power throughout the Vietnam War, and particularly of its large force of B-52s, which were in the inventory for nuclear operations, but also had a very effective conventional capability. The North Vietnamese developed a very sophisticated air-defence system, using mostly Soviet radars, guns, missiles and aircraft, but with some Chinese equipment as well.
Operation Linebacker II took place when President Richard Nixon decided to use air power as a reprisal when the North Vietnamese abandoned the Paris peace talks on 13 December 1972. In the first raid, on 18 December, 121 B-52s attacked targets in and around Hanoi, supported by ECM aircraft, F-111s attacking North Vietnamese fighter bases, and F-4 Phantoms sowing chaff corridors. The North Vietnamese launched over 200 surface-to-air missiles (SAMs), fired much anti-aircraft ammunition, and flew fighter sorties, bringing down three B-52s and damaging two others. The following night no US aircraft were lost, but on 20 December six B-52s were downed. US tactics were then amended, reducing losses on the next four days, and there was then a thirty-six-hour ‘Christmas truce’ before 113 B-52s in seven waves struck targets in and around Hanoi, Haiphong and Thai Nguyen during a fifteen-minute period. The defences were overwhelmed, and only two B-52s were shot down. The operation continued for another three days, and then the North Vietnamese signified their willingness to return to the negotiating table.
During the eleven days of Linebacker II 729 B-52 missions were flown and 49,000 bombs (13,605 tonnes) were dropped on thiry-four discrete targets. Fifteen B-52s were lost and nine damaged, all to SAMs.
* The first operational H-bomb, the US Mark 17, weighed 19,050 kg.
† Specifications of US and Soviet strategic bombers are given in Appendix 11.
* Specifications of various tanker aircraft are given in Appendix 12.