Introduction
Every action has an equal and opposite reaction, according to Newton’s third law of motion. A similar logic is applicable to the theory of warfare with a slight difference in that the reaction is opposite but may not necessarily be equal – it may be more or less than the action. According to this rule, any fresh offensive strategy immediately triggers a defensive response. The sword and the shield, the tank and the anti-tank weapons and aircraft and anti-aircraft systems are examples of this phenomenon at work.

The role and impact of air power rose exponentially since its introduction during World War I. Within a century of man’s first heavier than air flight, the use of the third dimension (that includes space) has assumed a dominant role in modern warfare. The emergence of air power was based on it being used specifically in the offensive role, notwithstanding its initial utility as only an observation platform. The modern combat aircraft is a potent offensive weapon having the ability to reach out and strike at tremendous distances with surgical precision and devastating effect. In any present day conflict, the side enjoying the freedom to exercise its air power in the offensive role would have a commanding advantage over its adversary. For the defenders, however, defence against the enemy’s air potential therefore, is equally critical. Without a provision for adequate defensive measures against the opponent’s air power potential, any war strategy, be it offensive or defensive is doomed. Air defence acts as the shield to the sword of air offensive and success in modern combat, will to a large extent depend as much on the air defence capability of a nation as on its air offensive potential. The two are opposite sides of the same coin – air power.

Development of Air Defence: A Historical Perspective

The Early Era
Since the beginning of air assaults using airplanes, the most potent anti-aircraft weapon has been the fighter interceptor. Between WW-I and the later half of WW II, early detection was a major problem for the defenders that gave an enormous advantage to the aggressors. Since successful detection and interception of ingressing attackers remained a slim probability, the air defence of the early era primarily relied on ground to air fire in the shape of guns and artillery. Camouflage/concealment/deception also formed an important ingredient of the air defence. These had limited effect on the raiders which led to the birth of the famous but as we now know erroneous dictum, “Bombers will always get through.” At that stage air offence appeared to have an upper hand over air defence. Air power however, could not and did not play a strategic role during World War I as the offensive capability of combat aircraft of that period was very limited. Inadequate air defence of the nation’s vital areas/vital points was not a debilitating weakness then.

Initial utility of aircraft during WW I was restricted to that of an observation platform and in the reconnaissance role over the battlefield and as the performance of the earlier flying machines improved air power began to assert itself more forcefully.
The most effective and lethal form of air defence over the battlefield during WW I was in the shape of fighter interceptors. Fighter aircraft were used both in the offensive role of knocking out the adversary’s attackers and in the defensive role to protect friendly attack formations from being disrupted by enemy fighters. A showdown between the opposing fighters to establish air control was the inevitable outcome. The concept of control of the air was born and that was and still remains the lynchpin around which all other aspects of air strategy revolve.

The Impact of Radar
The invention and deployment of radars during the early phases of WW II was a major breakthrough in air defence operations. With its aid, the raiders could now be detected early enough for the defending interceptors to react in time. Bomber formations no longer enjoyed the luxury of reaching their targets relatively unmolested. The opposing fighters began to exact a heavy toll of the attackers. Tactical and technological solutions were adopted to avoid or at least delay radar detection. To counter the interceptor threat, employment of fighters to escort the strike formations was adopted. The success of the strike package depended to a large extent on its ability to evade the enemy interceptors. Fighter interceptors on both sides became central to mounting of an effective air defence by the defenders and conducting an effective offensive air operation by the attacker.

Radars however, had limitations that the aggressors could successfully exploit. Their ability to distinguish aircraft from the ground clutter when the attackers approached at a low altitude was limited – in fact non-existent in the early versions of the radars. Subsequently technological advancement has overcome this handicap to a large extent but the range and with it the effectiveness of radars are still inhibited by the earth’s curvature that limits the maximum ranges of target acquisition to that of line of sight. To get a continuous low level coverage, a chain of radars along with sophisticated inter-connectivity and communication link is required. Because of the high cost involved and other operational and technical difficulties, not many nations have been able to achieve a complete continuous low level coverage of their entire airspace.

Between WW II and the end of the 20th century, nearly all offensive air operations were planned and conducted at low/ultra low altitudes in a bid to evade detection or at least to delay it for as long as possible.

Low level operations brought about their own sets of problems, collision (with the ground obstacles and birds) being one of them. High fuel consumption while operating at low altitudes for the jet powered combat aircraft thus limiting their range and endurance was another handicap. Low altitude navigation was far more demanding than high altitude navigation but with the advent of INS/GPS, this shortcoming has been overcome to some extent. While the approach to the target could be undertaken following a low level profile, the earlier munitions necessitated a delivery from a dive mode. The attackers had to climb up (pop up) close to the target to achieve the weapons delivery profile and during that period, they were exposed to a murderous volley of anti-aircraft fire and from shoulder mounted heat seeking missiles.

In the late 50s and early 60s of the 20th century, special low level delivery weapons were developed which could be released from a level run from a low altitude. This obviated the need for a pop up manoeuvre. The defenders countered this move by the deployment of wire tethered balloons thus forcing the attackers either to run the gauntlet of collision with the balloons with serious consequences or climbing up to a height where the effectiveness of ground based air defence weapons increases manifold. Till the introduction of PGMs towards the end of Vietnam War, bomb accuracy remained low requiring a fairly large number of attack aircraft to achieve the desired degree of destruction. Conducting successful raids against well-defended targets was a daunting task. Defence appeared to have an upper hand over offence during this period although through professional planning and execution, offence could still prevail as was displayed by Israel during their six day campaign in June 1967. New technologies would soon change the defensive / offensive balance, tilting the equilibrium to one side and then the other.

The significance and criticality of ground air defence systems appear to be inversely proportional to the effectiveness of the interceptor force - the stronger the interceptor fleet, the less reliance is put on the ground air defence elements. A side enjoying overwhelming advantage over its adversary in its air power projection can afford to scale down the ground air defence elements accordingly. Gulf Wars I and II vividly brought out this aspect. The manner in which the Allied/Coalition Forces were assembled in Saudi Arabia/Kuwait with total disregard to camouflage, concealment, and dispersion, displayed an utter contempt of the enemy air power potential. Even before the commencement of hostility when Iraqi Air Force’s considerable offensive assets (especially during Gulf War I) were intact, US commanders were supremely confident of the ability of their interceptors to successfully engage and destroy any Iraqi pre-emptive air strike package launched against the assembling formations. Ground air defence elements must have been in place as a precautionary measure and in the event they were not required in the pre-hostility phase as the Allied/Coalition Forces strong airborne air defence system was sufficient to have deterred the Iraqis from initiating any hostile air action. Even after the outbreak of hostility, the only ground defence elements to play any meaningful part by the Allied Forces were the Patriot missile batteries that were used to engage the Iraqi Scud missiles. Their other elements of ground air defence systems were barely tested.

The Present Era
Towards the later half of the 20th century, two major innovations have had a profound impact on both the offensive and defensive air operations.

First, advancement in technology, especially in the electromagnetic field led to the development of an effective means of suppressing the enemy air defence set up, primarily its electronic sensors and anti-aircraft missile/gun guidance systems. These missions, first used during the Vietnam War were given the acronym of SEAD (suppression of enemy air defence) – and they aimed at neutralizing the opponents electronic sensors and missile guidance platforms through Electronic Counter Measures (ECM) and the use of special munitions. Once the enemy’s radar network has been sufficiently degraded, the attackers could once again have the freedom of operating at medium/high altitudes, thus reducing and even obviating the risks associated with low level operations. SEAD operations can also neutralize the enemy medium and long range SAM threat as all such systems rely on electronic signals that can be disrupted through ECM. Stealth technology, which reduces the radar signature of the airborne platforms to very low levels, making them almost invisible further tilted the offensive/defensive balance in favour of the former.

The side that can conduct effective SEAD operations could once again enjoy the luxury of approaching their target without the fear of being disrupted by the opposing fighters and delivering their weapons load from an altitude staying well clear of the lethal ranges of anti-aircraft guns and shoulder fired, short range heat seeking missiles. Attacking from a height permits the use of very accurate laser guided/satellite guided bombs thereby drastically reducing the number of platforms required to achieve the desired degree of destruction. This strategy has been very successfully employed by USA/NATO forces during Operation Desert Storm, Deliberate Force, Enduring Freedom and the just concluded Gulf War II. During Operation Desert Storm (Gulf War-I), only the British Tornado attack aircraft used the low level ingress/delivery mode of attack because their special runway denial weapons had been designed for delivery from a low level profile only. In the event, Tornadoes suffered the highest attrition rate among the Allied forces, mostly to small arms fire and heat seeking SAMs.

On the defensive side, the development of airborne sensors provided a tremendous boost to the air defence elements. Airborne platforms like the USAF’s E-3C AWACS have a wide uninterrupted coverage of the airspace, unhindered by the earth’s curvature because these platforms operate from very high altitudes. Enemy aggressors can be picked up at a great distance and they can no longer mask themselves against the terrain by flying low. Now, the air defence interceptors can be vectored to engage the raiders well before the target. Modern AWACS also carry a wide range of ECM capability that can cause severe disruption in the communication set up within the strike package; they can also degrade the intercept radars of the aggressors thereby further deteriorating their situational awareness.

AWACS however, can be employed in the offensive role as well, with equal lethality – indeed USAF/NATO has employed them in such roles during all major offensives since the Vietnam War. AWACS in support of the attacking formations can pick up the enemy interceptor force at a distance, disrupt their communication network and blind their airborne intercept radars and can then guide the escort fighters to tackle the interceptors thus permitting the strike package to reach their target unmolested.

AWACS technology with its full complement is presently available only with USAF and NATO forces. Israel Air Force also, with the help of USA has acquired a high degree of sophistication in this field. All other nations including the Indian Air Force are striving hard to incorporate the system through outright purchase or indigenous development. The Indian and Israeli collaboration in this field and the reported sale clearance of “Phalcon” airborne radar system to India by Israel is an ominous development that can have a far reaching impact in the conventional power equation in the sub-continent, to the detriment of Pakistan.

Comparison of USA and USSR’s Air Defence Doctrines
On the face of it Air Defence doctrines of USA and the former USSR are fairly similar. They both rely on an interceptor force as the first line of defence complemented by layered ground defence network comprising anti-aircraft guns, various versions of SAMs covering the entire spectrum of the air space around the target and the full range of passive defence measures. The whole edifice is supported by an elaborate surveillance network using ground, airborne and even space based sensors. In the implementation phase, there is slight dissimilarity in that while USA’s air defence is the responsibility of USAF, in the Soviet hierarchy, air defence forces form an independent service, owning all air defence assets except for the interceptor force which remains a part of USSR Air Force but comes under operational control of USSR Air Defence Forces. Even this difference is narrowed down further by the fact that while USA’s air defence is the responsibility of USAF, its Air Defence Forces for the defence of Continental America is headed by a four star general, known as C.in.C NORAD.

The similarities between the USA and Soviet air defence models notwithstanding, there is a conceptual difference in the emphasis each pays on the two components of air defence – the interceptor force and the ground air defence weapons.

Traditionally, USA and its allies have relied on fighter interceptors as the main line of defence with ground based weapons as the second line. Development and deployment of high quality air superiority fighters have always remained the hallmark of USAF. From WW II onwards, USAF fighters have traditionally had an edge over their contemporaries. P-51 Mustang was the uncrowned king during WW II. F-86 Sabre followed and for some time F-4 Phantom was considered the world’s best combat aircraft of its time. In the late 70s, the F-15 Eagle ruled the roost and together with F-14s and F-18s of USN and to some extent F-16s, USAF air superiority fighters have always enjoyed a decisive edge over their rivals. The mantle will soon be taken over by USAF’s F-22 Raptor.

USSR by contrast has never had an edge over USA in this field. The Mig-15 was inferior to the F-86, Mig-21 to the F-4, Mig-29s to the F-14/15/16/18 series and even the latest SU series may be very impressive in their flight performance, they do not come close to the effectiveness of the USAF fighters which by virtue of their very superior electronic suites, radars, gun sights and air to air missiles are in a class of heir
own.

Lacking the ability to match USA and NATO forces in fighter performance, USSR and Warsaw pact countries had traditionally relied on ground defences, led by Surface to Air Missiles (SAMs) – they had no other option. The cold war period witnessed a bewildering array of SAMs that were developed and deployed by USSR and its allies. These covered practically the entire spectrum of air space, from low level up to the beginning of stratosphere. The initial versions of SAMs had severe limitations but the later ones were/are fairly lethal though they still remain susceptible to various countermeasures. Their real threat lay in the surprise factor, as the Americans found out to their chagrin in the shooting down of the U-2 spy plane in 1962 over Russia, and the Israeli discovered to their horror during the initial phase of the Yom Kipper War of 1973. Even the USAF got nasty jolts during the Vietnam War’s early stages and had to quickly come up with technological and tactical solutions to counter the SAM menace.
This efficacy of over dependence on ground based air defence systems was severely tested in the Middle East, where Egypt (till 1973), Iraq and Syria followed the Russian model whereas Israel had adopted the US one. Arab-Israel War of 1967 thoroughly exposed the weaknesses of Egyptian and Syrian air defence systems although it could be argued that at that point in time both Egypt and Syrian air defence networks did not fully represent the USSR model. However, by 1973, Egypt, Syria and Iraq had patterned their air defence networks by adopting the USSR philosophy. The Yom Kipper War was the first test of the effectiveness of the Soviet system when pitted against USA’s doctrinal approach to air power employment concepts in the shape of the Israeli Air Force.

The first round of Yom Kipper air war was won by Egypt where the dense air defence weaponry deployed by Egypt exacted a very heavy toll of Israeli attackers – according to Israel’s own admission, almost a hundred Israeli jets were shot down by a combination of SAMs and anti-aircraft artillery during the conflict. This extraordinary success can be partially attributed to a failure of Israeli intelligence where they were unaware of the performance and the density of the latest SAMs that were deployed over the battlefield and were caught by surprise. However, once the surprise factor was over, IAF was able to regroup, thanks largely to the American assistance and sustenance and soon had the measure of the SAMs. Control of the air was re-established by Israel Air Force and with it an impending defeat was averted and Israeli Defence Forces eventually ended the war on an advantageous footing and could have inflicted heavy defeat on Egypt and Syria but for the restraint that was imposed on them by their master, USA.

Egypt’s initial success came at a heavy price. While their ground based air defence weapons did exact a heavy toll of the Israelis, it was also responsible for up to 20 percent of combat losses suffered by Egypt through fratricide (friendly fire), the figure of 100 aircraft is quoted by most independent sources - an indication of severe mismanagement and lack of coordination between the Egyptian Air Defence forces and its Air Force. An Air Defence Service, independent of the Egyptian Air Force was one of the causes for this frighteningly high and unacceptable fratricide figure.
Yom Kipper war brought out some very valid lessons, both for the defensive and offensive forces. The lethality of modern SAMs combined with radar controlled guns could no longer be ignored and lack of knowledge of these systems would spell disaster for the attacking formations. Subsequently, the war lesson also brought out that the flexibility of manned aircraft gave it the resilience to counter the SAM threat adequately and in the absence of a potent interceptor force, the side banking more heavily on ground based air defence system will eventually lose out. This lesson was forcefully demonstrated by Israel again in the Bekka Valley operations in 1982. Taking advantage of technological breakthrough in the form of superior weaponry and sensors and with a complete picture of SAMs and other defences in the Valley, Israel Air Force practically annihilated the Syrian air defence elements on the ground and in the air in one of the most one-sided combats between two roughly numerically equal adversaries. These two wars and of course the operations that followed subsequently by USA in Kuwait, Bosnia, Kosovo, Afghanistan and Iraq has demonstrated beyond any shadow of doubt that any air defence effort sans an effective interceptor force can and will easily compromised.

Options for Pakistan
Within a decade of gaining independence, Pakistan had aligned itself with USA, both in the political and military fields. From 1954 to 1965, American arms aid flowed freely and besides US hardware in the shape of aircraft, radars and weapons, PAF was exposed to the western concept of air defence that relied heavily on a potent interceptor force. In less than ten years PAF had been transformed into one of the modern and well-equipped air forces in the region, with a strong bias towards air superiority fighters. Its operational training was honed to produce fighter pilots excelling in the air combat role. Even the basic flying training syllabus at PAF College/Academy Risalpur was designed to seek out and nurture the skills required from potential fighter pilots. Trainees not meeting those exacting standards were eliminated from the programme. After graduation the young officers were put through gruelling advanced fighter conversion and operational conversion courses before they became eligible to join the elite combat squadrons. Dropouts from these institutions were generally offered, what the service considered, less demanding systems like transports and helicopters. PAF was, and still is, a ‘fighter centric’ service.

The strategy served the PAF and the nation well during the 1965 India – Pakistan War where PAF, despite a sizeable numerical disparity, created and maintained favourable air situation throughout the campaign – thanks largely to the skills of its small band of fighter pilots.

The next round of India – Pakistan war occurred just six years later in 1971 and this time PAF faced a much improved opponent who had learnt some of the lessons of the earlier conflict. Also, the abrupt cessation of military aid by USA after 1965 had grievously hurt the PAF by adversely affecting its force structure and operational training; yet despite these handicaps PAF fighter pilots achieved a kill ratio of about 2:1 in their favour. By comparison, the ratio achieved during the 1965 conflict was 2.3:1. Since Pakistan lost the war, losing the eastern half of the country in the process, PAF’s otherwise sterling performance in the air combat role was of little avail.
From 1971 onward, the disparity between PAF and IAF continued to increase. Faced with crippling embargoes and being short of resources, PAF was unable to maintain a qualitative edge in combat aircraft over the IAF. It did get a short breather in the early 80s when following the Soviet invasion of Afghanistan, USA military embargo was lifted and PAF received 40 F16s, the most advanced light weight combat aircraft of its generation. For a brief while PAF again enjoyed a decisive superiority in the air superiority role but this advantage was short lived as India inducted over a hundred Mirage-2000s and Mig-29s, aircraft closely matching the F-16s in performance. PAF’s traditional technological edge by then had been completely eroded; in fact the balance now had shifted in favour of the IAF. By 1990, USA had slapped another arms embargo on Pakistan, this time on the nuclear issue, and PAF was once again left to fend for itself. It goes to the credit of the service and to its commanders that despite these debilitating actions PAF was able to maintain its operational status and credible air deterrence. It could however, no longer guarantee a favourable air situation over the entire air space of Pakistan and for the duration of the conflict. Increased reliance on ground air defence systems was the obvious alternate. Creation of Army Air Defence Command with its integral batteries of anti-aircraft artillery and SAMs with the ability to provide ground based air defence cover to its formations and units was the logical outcome.

The present air defence policy of Pakistan still follows the USA model but compared to the pre-1971 era, there has been an increased emphasis on ground air defence elements. The two operate in tandem. Given the reality on ground, this is a realistic policy but care must be exercised that the strengthening of the ground air defence elements must not occur at the cost of the interceptor force that must be the first line of defence, with the ground defences forming the second line. Air power history has given an unambiguous verdict – without an effective interceptor force, air defence will get compromised no matter how lethal and dense the ground air defences are made. Maintenance of a credible interceptor force capable of effectively challenging and blocking the IAF intruders is an inescapable requirement. Ground air defences can then deal with the remnants of the adversary’s strike force. A reversal of this policy, similar to the one that were employed by Egypt and Syria during the Yom Kipper War cannot and will not work, if history of air power lessons are anything to go by.

Conclusion
While air power is intrinsically an offensive force, for nations like Pakistan, facing an adversary many times its size, air defence is equally important. Adoption of a strategically defensive but tactically offensive concept of operations is the only realistic option.

Within the ambit of air defence, its two arms, the air interceptor force and the ground air defence elements together with a reliable surveillance system are both vital. Of the two, the interceptor force is the key ingredient and remains central to the viability of the entire concept of air defence. Emphasis on quality air superiority combat aircraft and excellence of its pilots in the air combat role had always been and must continue to be, the hallmark of the PAF.