THE IMPACT OF PRECISION-GUIDED
MUNITIONS ON WAR
Published in 1984 RUSI and Brassey's Defense Yearbook 237 (Royal United
Services Institute)
© 1983 Lance S. Davidson
PERHAPS the greatest military achievement in history was Hannibal's
crossing the Alps in 218 BC because he knew that Rome confidently expected
any threat to its security by the Carthaginians to come from the south,
Hannibal attacked from the north. Many innovations in war strategy or
technology have had a profound effect because their significance was
originally unappreciated. Recent public controversy has focused on the
strategic nuclear arms race but has largely overlooked the dimension of
tactical, or battlefield, warfare.
Modern tactical weapons called
Precision-Guided Munitions (PGM) may have a far greater impact than
nuclear arms on how war is waged. Unlike ICBMs, PGM have recently played
an important role in all major wars. These 'smart' weapons represent a
technological revolution - we can no longer ignore how they can restructure
the nature of war.
PGM are tactical weapons which are not just shot at a target - they are
guided to it.
They operate in all environments air-to- air,
surface-to-surface, air-to-surface, and surface-to-air. This expanding class
of bombs and missiles dramatically improves the probability of hitting - and
what is more important, eliminating targets over increasingly longer
ranges. PGM seek out their targets rather than follow a ballistic trajectory
subject to the laws of physics. Consequently, their accuracy is not as limited
by range, as is true for prior conventional weapons.
The sinking of HMS Sheffield by a single Argentine radar-guided Exocet
dramatized the impact PGM can have on modern warfare. Yet PGM can be
effective in many wartime situations. For example, a ship is patrolling still
waters, apparently safe from enemy fire hundreds of miles away. Emerging
from a little dot over the horizon, a radar-guided missile rips into the ship's
hull, turning it moments later onto an inferno of flotsam. Meanwhile, a tank
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crew is busily firing shells at advancing enemy troops, unable to respond in
time to a laser-homing anti-tank missile, about to imbed its shaped-charged
warhead deep into the tanks 10-inch thick armour. A heat-seeking
anti-aircraft missile elsewhere hurtles harmlessly past a fighter at 2000
mph, fooled by a decoy plume of exhaust gases released by the pilot's
defensive countermeasure equipment. The year of this fierce battle,
perhaps 1983.
PGM became known at the end of the Vietnam conflict and figured
prominently in the Middle East War of 1973. Yet guided weapons are not
new. In World War Two, the homing submarine torpedo was developed; the
Germans utilized radio-guided glide bombs in Italy and fired their V.1 'buzz'
bombs and V.2 rockets on London and Antwerp; the Japanese flew
kamikazes and rocket-powered manned Baka ('Stupid'). PGM now being
developed or deployed in large numbers by the US include the following
sample types:
TOW is an optically tracked, wire-guided anti-tank missile, using a
hollow charge, with a range about 3 kilometres (surface-to-surface);
Phoenix is a long-range missile used by Navy tactical aircraft, with
guidance by either an active or a semi-active radar homing device
(air-to-air);
Maverick is a missile guided by television, but more recent Maverick
models have been refined with laser and infrared homing (air-to-surface);
Harpoon is an anti-shipping missile with a range exceeding 90
kilometres and guided by a preprogrammed altitude reference with an
active radar seeker (surface-to surface);
Stinger is a shoulder-fired anti-aircraft missile with a range of up to 5
kilometres which uses proportional navigation and infrared homing for
guidance (surface-to-air).
Guided weapons are designed for use against targets whose locations can be
determined accurately. Before a designated target can be located and
destroyed, it first must be detected. Yet improvements in target acquisition
do not come easily. Inadequate visibility caused by poor weather or enemy
countermeasures compromises the sophisticated equipment's reliability.
Since the operation of many PGM is predicated on whether the target is
visible to an observer, their effectiveness will be impaired as long as they
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are unable to function in all weather conditions, at night, through smoke or
through heavy dust. Moreover, depending on the topography of the
battlefield, terrain features such as trees and ravines wreak havoc on
guidance systems. They provide camouflage, reduce contrast needed for
electro-optical guidance and are considerably more reflective than military
targets for laser beams.
Despite, or perhaps because of, the proliferation of nuclear weaponry,
conventional weapons technology has experienced a quantum leap forward
in sophistication. Innovations have been especially prominent in sensors for
detecting and locating the enemy under all visibility conditions and in ore
effective munitions which depend on seekers to lock on and home in on
targets. In addition to enhanced detection and guidance systems, recent
weapon refinements include improved missile and warhead design, vertical
launch capabilities and superior counter-countermeasures to protect the
PGM themselves from the enemy's defensive countermeasures.
Millimetre radar which can be applied in guidance for beam-riding missiles,
target designation and even space; operating in wavelengths no greater than
10 millimetres (or 4 one-hundredths of an inch), millimetre radar has better
resolution is more effective in the smoke, fog or clouds which often plague
battle areas, and provides better focused beams to thwart jamming than
does other radar. Cheaper, lighter and smaller infrared imaging devices,
such as pyroelectric imagers, which filter out the ground's natural
background of heat to lock onto moving land targets, will improve night-time
operation. Research and development programmers should not only
concentrate on reducing costs and refining PGM guidance for all-weather
performance, but also on making existing PGM systems more
automatic. Major strides in these areas will result in a much greater
presence of 'smart' weapons in combat arsenals worldwide.
To the extent PGM will supplement rather than substitute for individual
weapons systems, tactical doctrines will take longer to catch up with the
technology, so the full military benefit of guided weapons may be forfeited
for some time. Also, the target acquisition research process may lag behind
PGM development and deployment.
GUIDANCE
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Basic to the advent of guided weapons were powered flight in developing
missiles, and electromagnetic command links for correcting guidance errors
after launch. A host of unpredictable forces can affect a missile during
flight, including deviations in wind and air pressure, varying power plant
performance
control
system
malfunctions,
and
enemy
countermeasures. Unlike other projectiles constrained to unalterable flight
paths, PGM can continually modify theirs. The first step to improve missile
accuracy generally was to install inertial guidance systems instrategic
missiles, e.g. ICBMs, to direct them along predetermined trajectories
towards stationary targets. The internal system also was more immune than
external control contains within all necessary information and will not be
deceived during the flight. A self-contained guided missile is expensive,
however, and only effective for stationary targets.
The focus of PGM research has been to improve precision of weapon's
accuracies by guiding the munitions to their targets - stationary or
moving. Accordingly, internal missile brainwork or homing system, has
refined guidance. On-board automatic homing devices function in one or
more electromagnetic spectral regions where microwaves (radar), infrared
waves, or electro-optical waves (laser beams or television-tracking) are
propagated through space. The different homing system in this final stage
of the flight path enable a projectile to self-regulate its flight path. Instead
of always heading directly toward the target, newer PGM can anticipate a
moving target. The weapons have either an active, semi-active or passive
homing device to lock in on a target, ensuring that the missile's warhead will
detonate at the target's predicted position or at least within its lethal
envelope. In passive homing, a seeker utilizes electromagnetic radiations
naturally characteristic of the target; heat waves, light waves and sound
waves. Active guidance homes on signals of the target which were originally
sent by, and then reflected back to a sensor contained within the weapon
(or by an external source, thus semi-active).
For both homing techniques a seeker processes the electromagnetic signals
emanating from a target to generate automatic corrections to the missile's
flight controls. For example, a modern Maverick has its target illuminated
with a coded laser beam, and then a laser-seeking device in the projectile's
guidance system locks onto the laser beam reflected from the target. The
Walleye air-launched glide bomb also provides a stand-off capability for
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aircraft, but it uses television cameras; an image of the target filmed by the
camera is displayed on a monitor screen inside an aircraft so that the
observer is able to lock the bomb's electrooptical tracker onto the
target. The homing system in a Soviet SA-7 anti-aircraft missile is
infrared-seeking and it is attracted to the hot exhausts from aircraft
engines. One of the most common PGM deployed by armed forces worldwide
is the antitank TOW. Here, the operator, using his sights, directs the missile
to the target via electronic impulses transmitted along a wire connected to
the missile.
This homing feature allows PGM to deliver ordinance with extreme
accuracy. As a result of this characteristic, PGM system components must
be compatible - defence missiles should not home on defense units. PGM
equipped with anti-self homing devices enable the weapons to distinguish
between friend and foe. Also, limitations on such sophisticated weaponry
(particularly munitions' accuracy during darkness or inclement weather) are
slowly disappearing with improvements in the missile's electronic brains - its
guidance system.
COUNTERMEASURES
An intense enemy countermeasures environment would frustrate the proper
functioning of many current detection and guidance systems, which rely
upon or radiate electromagnetic energy in their operation. Electronic
countermeasures (ECM) exploit the electromagnetic spectrum to thwart
guided weapons. Perhaps the best countermeasure to a guided weapon is
another guided weapon. In their recent invasion of Lebanon, the Israelis
sent ahead remotely powered drones as decoys for, and to fix the location
of, Syrian Soviet-made surface-to-air missiles (SAM), which were so
devastating to Israeli aircraft in the early days of the 1973 war. Israeli F-16s
could then destroy the SAM sites whose locations had been revealed. One
popular form of ECM is to dispense from aircraft 'chaff', or quantities of
radar-reflecting material such as tinfoil, to create 'radar clutter'. Another
countermeasure - jamming - can confuse or deny target information to an
adversary using radar for target-fixing or guiding weapons. One form of
active jamming is to saturate enemy radar frequencies by transmitting
continuous noise and thereby degrade the enemy system. Alternatively,
ECM system could generate erroneous information either on the range or
bearing of a target by alternating pulses in time or creating powerful mimic
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pulses for the enemy's tracking system. Of course, due to mutual
interference, neither side can operate within those frequency bands for
target acquisition. A related aspect is that such ECM betray position or
indicate to the enemy that he has been detected, and can be traced and
destroyed by hostile missiles.
Because guided weapons use homing techniques operating in different
regions of the electromagnetic spectrum, not all countermeasures are
electronic. Other means can reduce potential targets' electromagnetic
'signatures' which PGM rely upon for guidance. Engines, gun muzzles, and
exhaust nozzles emit heat which make them vulnerable to infrared-seeking
PGM. Countermeasures include channeling exhaust gases elsewhere or using
decoys emanating even greater heat. To counter optical homing missiles,
non-reflective paints offer protection, and organic smoke generators or
weather modification techniques, like cloud seeding, can cause atmospheric
distortions. Camouflage remains an effective basic countermeasured
against most types of PGM.
Countermeasures suggest of course, enemy countermeasures. Because
guided weapons systems are susceptible to detection and can be confused,
a tactic is to influence the PGM-armed force's perceptions of the battle
situation. Electronic countermeasures (ECCM) by a PGM-armed force may
thwart these attempts. ECCM protecting guidance systems include signal
coding and using random or rapid variations in frequency. By sending
impulses in a designated code, a seeker will follow only the series of signals
received with prescribed randomness. If the enemy attempted to jam the
targeting missile's signal with interference, the seeker will search out a clear
one. So there is a trade-off: if a missile follows a prepackaged route and is
thus liable to miss if the target has moved, the missile is also more resistant
to countermeasures. Implicit in allowing for corrections to guide the missile
is the increased susceptibility, and remedy, to enemy ECM.
PGM are rapidly becoming prevalent in warfare, since greater assurance of
a direct hit is a marked technical advance over prior weapons. New sensor,
guidance and communications technologies will continue to provide PGM
with vastly superior accuracy over longer ranges.
Since the operation of many PGM is predicated on whether the target is
visible to an observer, their effectiveness will be impaired as long as they
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are unable to function in all weather conditions, at night, through smoke or
through heavy dust. Moreover, depending on the topography of the
battlefield, terrain features such as trees and ravines wreak havoc on
guidance systems. They provide camouflage, reduce contrast needed for
electro-optical guidance and are considerably more reflective than military
targets for laser beams.
Despite, or perhaps because of, the proliferation of nuclear weaponry,
conventional weapons technology has experienced a quantum leap forward
in sophistication. Innovations in have been especially prominent in sensors
for detecting and locating the enemy under all visibility conditions and in
more effective munitions which depend on seekers to lock on and home in
on targets. In addition to enhanced detection and guidance systems, recent
weapon refinements include improved missile and warhead design, vertical
launch capabilities and superior counter-countermeasures to protect the
PGM themselves from the enemy's defensive countermeasures.
Millimetre radar which can be applied in guidance for beam-riding missiles,
target designation and even space; operating in wavelengths no greater than
10 millimetres (or 4one-hundredths of an inch), millimetre radar ha better
resolution, is more effective in the smoke, fog or clouds which often plague
battle areas, and provides better focused beams to thwart jamming than
does other radar. Cheaper, lighter and smaller infrared imaging devices,
such as pyroelectric images, which filter out the ground's natural background
of heat to lock onto moving land targets, will improve night-time
operation. Research and development programmes should not only
concentrate on reducing costs and refining PGM guidance for all-weather
performance, but also on making existing PGM systems more
automatic. Major strides in these areas will result in a much greater
presence of 'smart' weapons in combat arsenals worldwide.
To the extent PGM will supplement rather than substitute for individual
weapons systems, tactical doctrines will take longer to catch up with the
technology, so the full military benefit of guided weapons may be forfeited
for some time. Also, the target acquisition research process may lag behind
PGM development and deployment.
PGM AND RIVAL SYSTEMS
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The litmus test for evaluating PGM is to compare them with rival systems.
Besides cost-effectiveness, another consideration is military effectiveness.
PGM will figure prominently in military planning only if novel doctrines of
warfare can accommodate the new technology.
PROLIFERATION
The effect of PGM on local and global conflicts is now the subject of heated
discussion among military and political leaders worldwide. Clearly, the
impact PGM can have on small Third World nations contrasts sharply with
that for the superpowers. The major powers have long been preoccupied
with keeping the lid down on nuclear proliferation to avert a local tinderbox
from erupting into World War Three. Now even the prospect of a
David-Goliath scenario involving some minor Third World nation with a
select few deadly PGM, holding at bay the forces of a superpower, has is
increased the risks of war. Stringent controls to prevent Third World
countries from acquiring nuclear weapons contrasts sharply with the brisk
arms trade flourishing in guided weapons. Production of such sophisticated
weapons is limited to a few nations, so the technology is imported. Like the
nuclear arms race between the superpowers, the conventional arms trade
with anyone willing to buy will go on unabated unless something is
done. The immediacy of the problem becomes apparent when it is
remembered that the incidence of armed conflict is so high in the Third
World. The arms trade is, to some extent, responsible for elevating
international tensions and even precipitating war. A major difficulty in
controlling the arms trade is the fierce competition among supplier nations
to improve their trade balance accounts. And supply decisions are often
interwoven with political and diplomatic, as well as economic, concerns. For
supplier nations like the US and the USSR, their power is extended virtually
cost-free by foreign troops fighting on foreign soil. While political pressures
would deter supplier nations from encouraging the proliferation of
sophisticated weapons to their own detriment, large transfer of relatively
unsophisticated, inexpensive PGM should prove, under most circumstances,
to be more than sufficient. British Harrier jets were shot from the skies over
the Falklands by weaponry the British had previously sold the
Argentines. But a supply nation has little leverage to use arms as an
instrument of political control since the recipient country can shop for arms
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from another exporting nation. Third World countries will continue to
besiege suppliers for arms, not only for expansive conquests, but for security
against external and even internal threats. The greatest resistance to a
concerted effort by the supplier nations to regulate or reduce the arms trade
would come from the Third World nations themselves, since such proposals
are resented as schemes interfering with their autonomy. Perhaps the more
successful approach to avert potential conflict is timely and effective
diplomacy.
An increasingly important spillover effect of arms trading is that guerrillas
can acquire the leakage. PGM-armed insurgents carrying out guerrilla
strikes against government troops and engaging in urban fighting can readily
incorporate PGM into their tactics. While insurgents do not expose
high-value targets, government forces certainly do. In contrast, even if
counter-insurgents used PGM, they would still, for the most part, be reduced
to time-proven tactics of attrition and weakening the peasant support
base. Thus, PGM used by government troops would not noticeably aid them
in their mission.
IMPACT OF PGM ON NUCLEAR WAR
The impact of this new class of conventional weapons on potential nuclear
war is difficult to assess. PGM offer a non-nuclear war-fighting capability
which can lower - or raise - the threshold of nuclear conflict. PGM are
prescribed for tactical combat and represent a decided advantage for the
forces fighting with PGM where neither adversary is equipped with nuclear
weapons. Under the circumstances, it is unlikely that a superpower ally
would be included to use nuclear weapons to support one side unless its own
immediate strategic interests were seriously threatened. For adversaries
equipped with nuclear weapons, PGM are of some consequence on the risk
of nuclear war.
On one hand, more accurate tactical weapons would provide an
intermediate-level substitute for nuclear weapons and thereby prevent
escalation into a nuclear conflict. This added dimension could end a conflict
before either side resorted to nuclear weapons. Many legislators support a
build-up of conventional forces as a greater buffer since outnumbered,
outgunned American and allied troops currently rely on a nuclear threat to
deter enemy acts of aggression. Civilian populations would further benefit
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because the nature of PGM is to zero in on other weapons with
electromagnetic signatures; these weapons would be used against military
rather than civilian, targets.
Of course, the use of smart weapons also could lower the nuclear
threshold. If an adversary were predisposed to use nuclear weapons in order
to win (or following the loss of) a war, PGM would escalate the war since
the main effect of PGM is to alter tactical battle capabilities. Thus, an
adversary could back itself into a wall by taking the defensive posture of
imminent use of nuclear weapons should it fact the possibility of
defeat. The other side's superior fighting capability, resulting from a larger
or more sophisticated arsenal of weapons might hasten the
decision. However, since any improvement in military capabilities could
precipitate such a posture, attributing the risk specifically to deployment of
PGM is misplaced.
Another reason why the nuclear threshold could be lowered is that
distinctions between conventional, tactical nuclear and strategic nuclear
forces could become increasingly nebulous. The molecular deployment of
troops for tactical use of PGM might be perceived as preparation to wage
nuclear war.
There would be a strong inclination by an adversary to
pre-empt since both fighting capabilities demand similar force
structures. Also, although PGM in some cases might substitute for tactical
nuclear systems, many new systems could be modified to deliver nuclear
weapons. To be sure, there could exist a strong tendency to sacrifice the
nuclear fire-break to obtain victory.
For years the central purpose of a strategic arms arsenal has been to avoid
nuclear war, not to fight one and 'win' it. Melvin Laird, Secretary of Defense
in the Nixon Administration, has noted: 'Nuclear weapons may be important
for political purposes, buy they are useless for military purposes... Our true
strategic military needs have little to do with nuclear weapons except to
deter their use against us.' The Reagan Administration contends that the US
must have nuclear superiority over the Soviets to be secure. But we need
not match the Soviets warhead for warhead as long as our existing weapons
are adequate to deter a 'rational' first strike. (Use of strategic weapons
unquestionably involves irrationality, but discussion of nuclear strategy is
fruitless unless we presume that leaders seek rational ends to be gained by
their use). Strong force levels and research and development must be
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maintained only to inflict unacceptable damage in the USSR, i.e., an assured
destructive capability, for a credible threat. Only a small proportion of our
nuclear warheads are needed to render catastrophic destruction to 40
percent of the Soviet population and 75 per cent of Soviet industrial capacity
concentrated in urban areas. Although the Soviets could still eventually
recover, disproportionately little destructive capability is added when more
warheads are delivered to dispersed areas. Even accounting for such
variables as launch malfunctions, inaccurate trajectories, defensive
measures and losses absorbed by a Soviet first strike, the remainder of our
strategic forces is redundant for discharging its objective to hold the USSR
civilian population hostage to an unacceptable retaliatory threat. To arm
for a first strike capability, pursuant to a counterforce strategy in which
targets are enemy offensive forces, requires larger strategic forces; yet long
range missile accuracy is an unverifiable unknown and such a strategy could
have adverse, rather than a positive, effect on US security. Funds currently
reserved for production of strategic weapons are far in excess of this
country's needs. That is, a disproportionate amount of US military
expenditures is funneled towards nuclear weapons rather than tactical
ones. Our huge strategic force levels are devoted only to protecting us
against a Soviet threat, yet a Third World brush fire also could ultimately
jeopardise our security. Our current military posture embraces the Middle
East, Central America, the Far East, and other war zones as well, and we
must possess the instruments to protect American interests early on. Budget
requests in 1983 for 51 tactical guided missile programmes totaled $7
billion, in contrast to the $23 billion allocated, excluding research and
development, for strategic forces. The US strategy of deterrence, based on
mass overkill, would not be debilitated if military funds appropriated for
nuclear weapons were instead ploughed back into the economy. Further,
some funds reserved for strategic nuclear forces should be diverted to refine
tactical weapons, particularly PGM.
Actually, the use of nuclear weapons in any conflict remains questionable
for two reasons. First, the nuclear threshold is quite high, militaristic
rhetoric notwithstanding. Strategic deterrence has worked very well over
the years to avoid nuclear conflict. Also alternative strategic weapons
(e.g. chemical and biological) provide an even more lethal second strike
capability than nuclear weapons, whose capabilities are best realized in a
first strike against hard targets (such as missile silos) containing a
counter-offensive threat.
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CONCLUSION
PGM - not nuclear weapons - are the tools with which military and foreign
policy will be shaped. The military applications of PGM are unlimited - in
air, land and sea they represent the future for weaponry. In order to exploit
the full potential of PGM, however, more resources will need to be diverted
from nuclear weapons can be reduced to help rebuild the US economy, a
portion must be diverted, to some extent, to tactical weapons production. The arms race in tactical weapons, unlike nuclear weapons, is
unrestrained. The horizon of cost-effective, all-weather, simply operated
PGM is not far off. An infallibly accurate guided weapon able to dispatch its
target under all visibility conditions will be Prometheus' encore.
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